Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Cells in Dengue Virus Infection In Vivo

Cells in Dengue Virus Infection In Vivo Hindawi Publishing Corporation Advances in Virology Volume 2010, Article ID 164878, 15 pages doi:10.1155/2010/164878 Review Article 1, 2 1, 3 3 1 Sansanee Noisakran, Nattawat Onlamoon, Pucharee Songprakhon, Hui-Mien Hsiao, 4 1 Kulkanya Chokephaibulkit, and Guey Chuen Perng Department of Pathology and Laboratory Medicine, Dental School Building, Emory Vaccine Center, Emory University School of Medicine, 1462 Clifton Road, Atlanta, GA 30322, USA Medical Biotechnology Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathumthani 12120, Thailand Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand Department of Pediatrics, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand Correspondence should be addressed to Guey Chuen Perng, gperng@emory.edu Received 9 March 2010; Accepted 6 July 2010 Academic Editor: Eric O. Freed Copyright © 2010 Sansanee Noisakran et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Dengue has been recognized as one of the most important vector-borne emerging infectious diseases globally. Though dengue normally causes a self-limiting infection, some patients may develop a life-threatening illness, dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS). The reason why DHF/DSS occurs in certain individuals is unclear. Studies in the endemic regions suggest that the preexisting antibodies are a risk factor for DHF/DSS. Viremia and thrombocytopenia are the key clinical features of dengue virus infection in patients. The amounts of virus circulating in patients are highly correlated with severe dengue disease, DHF/DSS. Also, the disturbance, mainly a transient depression, of hematological cells is a critical clinical finding in acute dengue patients. However, the cells responsible for the dengue viremia are unresolved in spite of the intensive efforts been made. Dengue virus appears to replicate and proliferate in many adapted cell lines, but these in vitro properties are extremely difficult to be reproduced in primary cells or in vivo. This paper summarizes reports on the permissive cells in vitro and in vivo and suggests a hematological cell lineage for dengue virus infection in vivo, with the hope that a new focus will shed light on further understanding of the complexities of dengue disease. 1. Introduction fever annually, and about 200,000 to 500,000 of these are DHF/DSS, which has a mortality rate about 1%–5%, mainly Dengue is one of the most important mosquito-borne viral in children under 15 years of age [3]. diseases affecting humans, with over half of the world’s Clinically, DF and DHF/DSS have several common population living in areas at risk. Originally, dengue virus features: viremia lasting for 5 to 8 days, fever persisting for infections occurred mainly as epidemics in tropical and 2 to 7 days, headache, myalgia, bone/joint pain, and rash, subtropical countries. But over time, with increasing glob- often accompanied by leucopenia. Occasionally variable alization and the geographic spread of inhabitants of Aedes degrees of thrombocytopenia and cutaneous hemorrhage are aegyti and Aedes albopictus mosquitoes, the dominant vectors observed. More severe cases with incapacitating bone/joint for dengue virus transmission, dengue virus infection has pain (“break-bone-fever”) are common among adults. The steadily penetrated every corner of the world [1, 2]. Dengue pathological hallmarks that determine disease severity and virus has four serotypes, and each of them can cause distinguish DHF from DF and other viral hemorrhagic a spectrum of diseases ranging from asymptomatic, mild fevers are plasma/vascular leakage resulting from increased febrile (dengue fever, DF) to a life-threatening illness, dengue vascular permeability and abnormal hemostasis. Factors and hemorrhagic fever (DHF)/dengue shock syndrome (DSS). biomarkers that can be used to identify those individuals at Approximately 50 to 100 million people contract dengue risk for DHF/DSS are not known. Epidemiological evidence 2 Advances in Virology suggests that preexisting immunity to dengue virus can demonstrable neutralizing antibody to all four dengue enhance disease upon sequential infections [4]. Although serotypes [8], viremia still occurs in some of these popula- intense efforts have been made to identify the etiology of tions upon bitten by mosquitoes carrying infectious dengue DHF/DSS, the potential mechanisms involved in the patho- virus. The reasons why certain individuals developed clinical genesis of DHF/DSS remain an enigma; in large part due to illness are not known, although an individual’s genetic the lack of a satisfactory animal model that recapitulates the background, the interval between reinfection, sequence of clinical sequelae of human dengue virus infection. Currently, infection by specific serotype, and quality of immune there are no effective vaccines or therapeutic drugs available responses may partially account for the differences [4, 8]. to prevent or treat dengue virus infection. The importance of Since identifying the permissive cell lineage(s) in vivo may the dengue, in particular the more severe and potential dire uncover the underlying mechanisms leading to DHF/DSS consequences including death in DHF/DSS, has caught the and aid in vaccine and antiviral drug development, the attention of public concerns, and the NIAID/NIH has listed source(s) of circulating virus in acute dengue patients has dengue virusasaCategory Aprioritybiothreatpathogen been the central focus for several decades. In spite of the [5]. The recent outbreak in Brazil highlights the possibility efforts made to identify these cell(s), the question remains of dengue virus spread to North Americas, thus providing a elusive. potential public health threat to the US as outlined by Dr. Fauci, NIAID [6]. 4. In Vitro Studies Dengue is a timing illness, in other words, the progres- sion to clinical manifestations may differ among infected In vitro, numerous primary cell lineages and established individuals, which has caused variation in time points cell lines have been studied for their relative permissive- of specimen sampling. Currently, many of the descriptive ness for dengue virus infection, including endothelial and events or associated factors related to dengue or dengue fibroblast cells, myeloid-derived cells, and lymphocytes [9– pathogenesis are predominantly derived from the specimens 17]. Although some of the cells defined in vitro could be obtained at the appearance of clinical signs of dengue. permissive cells for dengue virus replication in vivo [18– Because of the lack of early time point in patient samples 21], the actual phenotypes of these cells have not been and suitable or satisfactory animal models, a comprehensive delineated or defined in detail. Consequently, conflicting picture of the events cumulating in DHF/DSS pathogenesis, reports abound in the literature. such as the role of enhancing antibodies, the requirement for Historically, dengue virus has been isolated from poly- specific sequence of infection, the types of cells infected, as morphonuclear leukocytes (PMNs) [22], adherent cells well as the nature and source of the mediators responsible for presumed to be phagocytic monocytes or macrophages [23], increased vascular permeability, is unresolved and constantly and nonadherent leukocytes [24, 25] from dengue patients. in debate. Additionally, since this virus is delivered to its host via In this paper, we summarize or discuss what has been mosquito bites to the skin, the human Langerhans cells, reported thus far on the permissive cells for dengue virus skin cells with a morphology and function similar to that of infection both in vitro and in vivo and propose a new poten- dendritic cells, have been suggested to be a potential target tial permissive cell type that has been neglected frequently for dengue virus infection [26]. Several in vitro studies utiliz- anddeservesmuchmoreattention. ing myeloid-derived dendritic cells have been documented, which suggest the permissive cells upon contact with dengue virus are monocytoid-derived DC-SIGN bearing DCs and 2. Dengue Viruses mannose receptor bearing macrophages [27–33]. In this regard, however, other evidence suggests that Langerhans Dengue viruses, similar to other flaviviruses, possess a pos- and/or dendritic cells are probably implementing their itive single-stranded RNA genome packaged inside a core normal immune functions, such as taking up antigens for protein, which is surrounded by an icosahedral scaffold processing and presenting them to the adaptive immune and encapsidated by a lipid envelope. Its 11 kb genome cells, instead of serving as the reservoir cell for dengue functions similar to mRNA, encoding a polyprotein which virus [21, 34–36]. In addition, it should be noted that upon translation is cleaved into three structural proteins atypical lymphocytes, which may be cells closely related to (C, prM/M, and E) and seven nonstructural proteins (NS1, CD19 B cells, since there is a correlation between these NS2A, NS2B, NS3, NS4A, NS4B, and NS5) by viral or host two cell populations [37], have been regularly reported proteases. Since dengue viral genome can function as mRNA, to be found in increasing frequency, circulating in the if the viral RNA can be delivered into a cell’s cytoplasm peripheral blood of naturally dengue-virus-infected human through biologically active vesicles, translation and genome patients [38, 39]. This uncharacterized cell lineage has been synthesis can occur accordingly [7]. suggested as a potential host cell for the replication of dengue virus in infected patients [22]. As a whole, only a small subpopulation of cells in peripheral blood appears to be 3. Dengue Viremia infected by dengue virus [22, 23], but the phenotype of this Viremia is a common clinical manifestation in several severe subpopulation has yet to be fully characterized. A view on the viral infections. However, dengue viremia is unique because selected suggestive permissive cells is elaborated in a bit more in endemic regions, where majority of the population has detail. Advances in Virology 3 5. Skin Innate Immune Cells of defense mechanism. Thus, if these dendritic cells are permissive as others suggested [27–33], we would anticipate Dengue disease is introduced to its hosts by the bite of quite high incidence of the dengue cases in endemic regions mosquitoes carrying infectious virus. The first obstacle that during the rainy season. The critical role of these antigen the mosquito encounters is the physical barrier of the presenting cells (APCs) is to ingest foreign particles including skin, which is composed of several layers of keratinocytes viruses, process these materials while migrating to the interspersed with a network of capillaries (Figure 1). Ker- regional lymph nodes. Here, the APCs can present the atinocytes are on the outermost epidermal layer of the skin, foreign proteins to other immune cells, such as T cells, are endowed with Toll-like-receptors (TLR) [40], and may to initiate the cascade of the adaptive immune responses, be considered a component of the primary innate immune including antibody production. Dendritic cells, therefore, system. Langerhans cells mainly reside in the thin layer of may be more important for the induction of the host’s the epidermis, which does not contain capillaries, while defense. Importantly, it is of benefit to the host that the virus dendritic cells are predominantly in the thicker dermis layer, be engulfed and processed in order to generate an adequate which is filled with capillaries. Although Langerhans cells, immune response against the invading pathogen and protect in general, have the same phenotype as dendritic cells, the host from further infection. Since such phagocytic cells and is impossible to distinguish activated Langerhans cells are the first line of defense in our body, this may perhaps from dendritic cells by morphological appearance, numerous explain why a majority of dengue cases are asymptomatic. studies indicate that biological activities are discernible Interestingly, apoptotic keratinocytes and dendritic cells between these two cell types [41–44]. Many interesting are observed in human skin explants when dengue virus questions can be asked. How does dengue virus interact with is directly injected into the epidermis with a fine needle skin cells during mosquito probing prior to penetration? [35]. Furthermore, others have observed that mosquitoes How deep does the mosquito fascicle penetrate into the skin? can deposit high doses of virus extravascularly as they probe How does dengue virus behave upon contacting epidermal and feed on the host, while only a small amount of virus and dermal innate immune cells after the mosquito fascicle is injected directly into the blood [50]. Considering the fact penetrates? And how does dengue virus get deposited and that a majority of dengue virus infections are asymptomatic, disseminated during the engorgement period while the this evidence suggests that the role of dendritic cells at the site mosquito imbibes the blood? The answers to these questions of fascicle penetration is to eliminate or temporarily contain can elucidate how the fates of the cells on or in the skin are the intruders and thereby prevent or reduce the dissemina- orchestrated. tion of dengue virus. However, the role of keratinocytes and dendritic cells in clearance of dengue virus remains to be further investigated. 6. Mosquito Imbibing Gordon and Lumsden, the authors of a historical in vivo 8. Monocytes/Macrophages frog’s web paper in 1939, observed that the mosquito’s proboscis is flexible and predominantly imbibes blood Since dengue viral antigens are detectable in adherent cells directly from the capillary and only occasionally from obtained from the peripheral blood of dengue patients, the pools formed in the tissues by the leakage of blood monocytes and/or macrophages have been an assumptive from the capillary previously lacerated by the mosquito’s target cell for more than three decades. With the high level proboscis [45]. This study is later confirmed in mice ear and of interest in the pathogenesis of DHF/DSS, intensive efforts human beings implementing the same experimental designs have been made to identify the infected monocytes and/or [46, 47]. The dimensions of an Aedes aegypti fascicle are macrophages in the peripheral blood of infected patients, typically 1.8 mm in length with an internal radius of 10 μm andsomesuggestivesuccesseshavebeendocumented. [48] and typically engorge a blood meal of 4.2 μl in 141s However, dengue is a timing disease. Specimens collected [48]. It is estimated that during imbibing, approximately from dengue patients are often after the onset of clinical 50% (∼0.9 mm) of the fascicle penetrates into skin [49], manifestations; therefore, the intervals prior to symptoms suggesting that the location of blood drawn from is the developed are different among individuals and are likely capillary-rich dermis layer, implicating that pathogens may at the peak of dengue viremia, and autopsy samplings are be directly injected into the blood. always at the convalescent stage or later. Within the context, identifying a cell that is positive for dengue viral antigens in collected specimens requires meticulous investigations and 7. Dendritic and Langerhans Cells cautious interpretations. Although recently researchers are Mosquito probing, penetration, and feeding on the surface attempting to address the issue with small animal models, of the skin is easily interrupted by the movement of the such as the AG129 mice experimentally infected with dengue host. Unsuccessful imbibing may result in a certain amount virus, the major pitfall of this model is that mice have of virus deposited on the outermost layers of skin, where a defective interferon response, which has been shown to keratinocytes, Langerhans, and dendritic cells may encounter play averycriticalroleincontrolling virusreplication and the virus. The delicate alarm system of the skin can sense the proliferation. Consequently, dengue viral RNA or antigens probing of the mosquito and the penetration of the fascicle, are observed in almost all the cells and organs that have been potentially initiating a signaling cascade and the activation investigated [18, 21]. Within the same content, this same 4 Advances in Virology DC LC Keratinocytes Stratum corneum (0.01 − 0.02 mm) Epidermis (0.03 − 0.13 mm) Basal cells Dermis (1.1mm) Capillary Subcutaneous fat (1.2 mm) Muscle base Figure 1: A schematic diagram of the skin. A cartoon drawing based upon the textbook descriptions of the thickness of outer skin layers. Only layers relevant to the subject are shown. LC, Langerhans cells; DC, dendritic cells; Capillary, green and red internetworks. group investigated the autopsy tissues from patients who infection. However, if stainings included a specific marker died of dengue virus infection. The authors showed that for platelets and/or megakaryocytes, it may help distinguish human tissues and the corresponding mice AG129 tissues the phenotype of the dengue virus infected cells. Although were positive for dengue virus NS3 antigen, concluding these studies demonstrated that dengue viral antigens or that these cells propagated virus. However, the phenotypic RNA were observed in certain cell populations, the definitive markers of the cells that were positive for dengue viral phenotype was not determined. Therefore, in vivo, the antigen were not confirmed, and thus a conclusion was cell(s) accounting for viremia during dengue virus infection drawn based upon the similarities between humans and remains an enigma. mice. Also, a new finding suggests that liver sinusoidal CD31+ endothelial cells in AG129 mice are positive for 9. Historical Observations dengue viral antigen and can support the antibody-mediated infection [21]. However, evidence indicates that there are Retrospective literature reviews reveal that in bone mar- many differences in immunological and antiviral responses rows aspirated during the recovery stage or immediately between humans and mice [51–53]. Thus, clarifications of after death, phagocytic clasmatocytes contain normoblastic, the role of monocytes and macrophages in dengue virus lymphocytic, granulocytic, erythrocytic, and platelet-like infection in vivo are urgently needed. This notion is also remnants in their cytoplasm [60–62]. Infected leukocytes (or applied to the paper published by Jessie et al. [20], in which monocytes) are frequently present on the last day, at the end the cell phenotype markers in those cells positive staining for of viremia, or the day after the disappearance of the virus either dengue viral antigens or RNA, were not confirmed. from the plasma [63], suggesting that leukocytes may play an In addition, Durbin et al. [19] has performed an exten- essential phagocytic role in the clearance of circulating virus. sive phenotyping of PBMCs during acute dengue illness, Recently, the phagocytic phenomenon has been confirmed in and the results suggest that quite a few immune cells with dengue hemorrhagic nonhuman primate model [64]. Due to variouscellsurface markersare positive forviral antigens, difficulties and inconsistencies in identifying the cell lineages prM or NS3. Recently, in a study with AG129 mice, dengue responsible for dengue viremia at the acute stage, monocytes antigens are seen in CD31 liver cells stained with the same and/or macrophages are gradually being assumed as the antibody [21]. However, these observations can be explained main cells for dengue virus propagation for the following by several factors. One of such alternative explanation is reasons: (i) like the cells that can propagate the virus, they platelet-leukocyte aggregation, which has been documented canadheretocellculture flasks[63, 65], (ii) they are capable to occur in a number of physiological and pathological of phagocytosis [23, 66], and (iii) infrequently observed states [54–58] and has been implicated in contributing dengue viral antigens in cells with a similar morphology in to inflammation [54, 57, 59]. Another possibility is that tissues obtained postmortem [20, 67, 68]. These observations multiple cell types can be stained with the same cell markers; then led to the postulated hypothesis of antibody-dependent for example, megakaryocytes and platelets can be stained enhancement (ADE) [69] in an attempt to explain the with CD31-specific antibody. Whether the virus actively epidemiological observation in which secondary infection replicates in these cells was not shown, and thus the dengue with subsequent heterologous dengue serotypes is a risk viral antigen detected in these cells may be the result of factor for DHF/DSS [70]. The ADE theory is used to engulfed materials or undigested protein residue via in vivo explain the severe dengue virus infection; antibody to the deposition of virus-antibody complexes rather than direct first infection may not be sufficient enough to neutralize Advances in Virology 5 a heterologous infection, and this partial cross-reacting anti- cancer cells, such as lymphoma and leukemia and established body (or subneutralizing antibody) may promote Fc-bearing immortalized cell lines [84–88]. This line of evidence may, to cells such as monocytes and macrophages to opsonize the some extent, explain why cell lines, such as Vero and K562 virus, leading to increased virus production. cells, which lack a functional interferon system, are highly permissive to dengue virus infection. In addition, activation However, studies have shown that some hematopoietic of interferon-stimulated genes are the constant findings in cells have the adherence and phagocytic property as well cells with relatively poor permissive for dengue virus [14, [71], and consequently reports on the ADE hypothesis 89, 90] and in specimens obtained in dengue-virus-infected are in debate. In support of this view, in the presence of humans and rhesus monkeys [89, 91, 92]. Within the same subneutralizing antibody, a low percentage of dengue virus content, it is interesting to review what has been investigated infected monocytes and/or macrophages can be observed in paucity of dengue animal models. in vitro [72–74]. On the contrary, some reports indicate that monocytes and/or macrophages have a different role— to protect against dengue virus replication. Evidences in 11. In Vivo Animal Studies support of this view include: (i) monocytes/macrophages Currently, no perfect animal model that recapitulates the undergo apoptosis in contact with dengue virus, (ii) they cardinal features of human DHF/DSS is available, even are capable of phagocytosis, (iii) they phagocytose infected though a recent dengue hemorrhagic monkey model appears apoptotic cells or apoptotic bodies, and (iv) they upregulate to be promising for dengue hemorrhagic investigation [64]. immune responses through autocrine or paracrine cytokine Since understanding the mechanisms leading to viremia mechanisms [15, 64, 75–80]. and disease is necessary for vaccine and antiviral drug An interesting discrepancy abounds. If monocytes and/or development, efforts have been made to search and/or macrophages are the cells accounting for viremia during generate a suitable dengue animal model. The readers should acute infection, why is it so difficult to detect the viral refer to recent review articles on the subject in smaller antigens in peripheral blood cells obtained from acute animals [93, 94]. This paper focuses mainly on why dengue dengue patients? The aforementioned scenario—protective viremia is seen in these animal models. against dengue virus may account for the answer. With the The absence of disease symptoms, virus replication, and evidence available in vivo to date, it is more reasonable to viremia in the serum of laboratory immunocompetent mice assume that the presence of dengue viral antigens within strains [95–98] indicates these mice are not suitable to study monocytes in samples obtained towards the end of the the cells permissive for dengue virus infection. In contrast, acute infection period may be the result of phagocytosis and in immunocompromised mice, such as AG129, A/J, and viral clearance. Interestingly, a recent report also suggests −/− STAT mice [99–102], dengue viremia can be observed, a prominent role of monocytes and/or macrophages in the though to some levels, in serum and in almost all the major control of dengue virus in infected mice [81]. Unfortunately, organs studied. Thus, in immunocompromised mice, the the role of monocytes and/or macrophages in dengue virus interferon system may have defects that enhance disease infection has drawn the center attention for more than unnaturally. Taking this into account, it is improbable that three decades, yet the importance they play in the patho- identification of the potential permissive cells for dengue genesis of DHF/DSS is still unclear. Recently, an immuno- virus replication will result from investigations with this competent nonhuman primate model recapitulating the model. In studies involving human chimeric mice, dengue dengue hemorrhagic is available [64], the mystified issue virus appears to be detected predominantly in the human on the role of monocytes and/or macrophages in dengue implanted or immortalized cells [103–109], suggesting that virus infection may be further delineated and hopefully only the cells of human origin are infected and mice tissue resolved. can not support viremia. Nevertheless, as a whole, despite having a few drawbacks, such as low to undetectable dengue 10. Biological Characteristics in antibody in serum, and to some extent, lack of typical characteristics of dengue disease [108], currently a small Cells Infected by Dengue Virus animal model with detectable viremia, perhaps would be The reason why dengue viruses are capable of infecting ideal for the initial screening of antiviral compounds and/or a wide range of immortalized cell lines, such as myeloid- vaccine toxicity studies. However, the rhesus macaque animal originated, B, T, fibroblast, and endothelial cells but yet model is more appropriate for investigations involving the comparatively poor at replicating in primary cells is currently cells responsible for dengue viremia. unknown. Perhaps, it is likely that cell factors that are altered The only large animal species besides humans that are in immortalized cell lines contribute to this differential known to be naturally infected and can be experimentally permissiveness. Immortalized cell lines are normally trans- infected by the parenteral route are monkeys [110–115] formed with viruses, such as SV40 or EBV, which encode viral and apes [97]. The antibody response and viremia levels gene products that have an effect on interferon-signaling. in monkeys are similar to that seen in humans [111], and Interestingly, among the cell mediator repertoire, interferon therefore they have been viewed as an acceptable animal expression appears to be a very crucial element limiting model to study virological and immunological aspects in the propagation of dengue virus [14, 82, 83]. In addition, experimental dengue virus infections [116–119]. In addition, defects in interferon signaling pathway has been shown in it has been well documented that in all aspects, the cell 6 Advances in Virology composition of rhesus macaque bone marrow is very similar patients remain unknown. Also, the interactions of dengue to that of humans [120, 121] and is highlighted by the virus with platelets, including entry and possible virus fact that the parameters established for blood transfusions production, have not been investigated. in monkeys has served as an important guide for these We have proposed that platelets may be a critical procedures in clinical studies [122]. Furthermore, a recent element in early dengue virus infection [131–133], which report demonstrated a recapitulation of human dengue hem- may partially account for the dysfunction of platelets. orrhagic in rhesus monkeys via intravenous administration Subsequent systematic investigations, with biological assays of high doses of dengue virus [64]. Even though the level and and electron microscopy, reveal that dengue viral RNA, magnitude of dengue viremia is slightly lower than that of either the positive stranded genome or negative stranded humans, this model displayed disease symptoms and thus is template, and the presence of mature virus-like particles, a better animal to investigate the source of dengue viremia. are consistently observed in platelets isolated from dengue However, a systematic investigation to identify the potential confirmed patients during the acute phase of infection cells for dengue viremia in this model has not been explored [132, 133]. A micrograph of dengue virus-like particles in depth due to limited accessibility of the resources and the within platelets isolated from confirmed dengue patients is high cost of the model. Thus, this topic will be evaluated with depicted (Figure 2). Typical clustering of dengue virus-like samples collected from dengue-infected patients. particles surrounded by a vesicle was observed in platelets (Figure 2(a)), and occasionally single or isolated dengue virus-like particles were observed [133]. Infrequently, dengue 12. In Vivo Dengue Patients virus-like particle with a fuzzy morphology were observed associated with or released from platelets (Figure 2(b)). Studies over the years with specimens collected from the However, we could not rule out the possibility that these peripheral blood of dengue patients reveal that virus can be dengue virus-like particles containing platelets are in the recovered or detected in a variety of cells. However, a general category of megakaryocyte-derived microparticles [134]. In consensus concerning which cell lineages are involved in addition, immunofluorescent staining of platelets isolated dengue viremia has never been conclusive, partly due to the from confirmed dengue patients reveals that viral antigens variation of timing in specimen collection. Upon admission can be observed not only in platelets, but also in cells with to the hospital with clinical symptoms, patients are always the similar morphology as proplatelets (Figure 3(a)), while several days after the infection and frequently at the peak some dengue viral antigens were observed in presumably or downturn in viremia. By that time, a complex network the micromegakaryocytes (Figure 3(b)). This observation of immune responses initiated and is in the action of viral is consistent with early reports by Nelson et al. [61, 126], clearance. Perhaps, this may explain why immune cells are who originally observed the presence of immature and commonly associated with the detection and/or isolation of nonplatelet forming megakaryocytes circulating in dengue virus in dengue patients [24]. Thus, the cells that are infected patients and by Bhamarapravati and Boonyapaknavik [135], early, before the peak in viremia, and accounting for dengue who noted that positive staining for dengue viral antigen viremia are still unknown. in human tissues was demonstrated only in the lymphoid- like cells. Interestingly, the nucleated micromegakaryocytes, 12.1. Platelets in Dengue. One of the important clinical which are similar in size and morphology to lymphocytes, hallmarks in dengue virus infection in patients is platelet have been well documented [136, 137]. The presence of micromegakaryocytes, as opposed to megakaryocytes, dysfunction, which occurs throughout the acute phase, and/or thrombocytopenia, which frequently occurs at the suggests that production of platelets from bone marrow defebrile stage, thus this is a subject of interest, especially increases in response to dysfunctional or low numbers of in understanding the possible mechanisms leading to the platelets in the circulation of acute dengue patients. observed phenomena. There are a few proposed mechanisms Although platelets do not have a nucleus, they possess functional spliceosomes that are able to process pre-mRNAs that may explain platelet dysfunction and/or thrombocy- topenia: (i) decreased production, (ii) direct infection by into mature mRNA, from which proteins can be translated virus, (iii) increased consumption, or (iv) immune-complex and processed [138, 139]. In vitro experiments were set up to lysis. The first mechanism has been observed. Early in investigate the susceptibility of platelets to support dengue infection of dengue virus, it exerts a transient depressive virus production, which may directly contribute to the effect on megakaryocytes in the bone marrow [123–126], platelet dysfunction. A low level of dengue virus production which subsequently becomes normocellular or hypercellular could occur in infected platelets with the peak occurring at 18 a few days after onset of fever [61, 124, 126]. In vitro hours post infection (Figure 4), suggesting that dengue virus and in vivo, dengue virus has been demonstrated to have is capable of replicating in platelets and dengue viral antigens toxic effects on platelets in the presence and absence of may be expressed on the surface of platelets. Alternatively, acute and convalescent patient serum, lending some support the moderate viremia changes may result from the transient ability of platelets reproduction in culture conditions [140], for the second mechanism [127–129]. In addition, dengue viral RNA has been isolated from or detected in platelets which may have the capacity of capturing and releasing isolated from secondary dengue virus infected patients [130]. dengue viruses in later hours. Perhaps, this may account However, the precise mechanisms for the development of for the rise of platelet-associated antibodies (PAIgM/IgG) dysfunctional platelets and thrombocytopenia in dengue during acute dengue virus infection [130] and the increased Advances in Virology 7 100 nm 143 nm 250 nm (a) (b) Figure 2: Dengue virus-like particles in platelets isolated from confirmed dengue patients. Platelets were isolated from confirmed dengue patients at the acute stage and subjected to electron microscopy. (a) Dengue virus-like particles were observed inside vesicle compartment (red arrow) and a particle appeared to be on its way budding out into the vesicle (blue arrow). (b) A single fuzzy virus-like particle was released from platelet (red arrow head). Red circle indicates the enlarged area. Insert is the platelets. incidence of phagocytosis of platelets from patients with platelets are demarcated from the membrane of megakary- secondary infections by human macrophages [78]. In addi- ocytes, which may result in heterogeneous populations of tion, administration of intravenous immunoglobulin, which platelets. This heterogeneity of platelet alloantigen referred saturates phagocytosis and impedes antibody production, to as human platelet alloantigen (HPA) polymorphism in the lacked efficacy when used to treat severe thrombocytopenic literature, and how it contributes to dengue virus infection patients with secondary dengue virus infection [141]. As a and dengue disease severity warrants further investigation. whole, these evidences suggest that dengue virus may take a ride and experience ongoing maturation within platelets 12.2. Megakaryocyte-Erythroid Progenitor (MEP) Cells in produced from infected progenitor megakaryocytes. Dengue. Hematopoietic progenitor cells (HPCs) normally Platelets are anucleate cells that have hemostatic and reside in bone marrow but can be mobilized to peripheral inflammatory functions [142, 143] and are composed of blood by stimulation with cytokines/chemokines. During a concentrate of megakaryocyte membrane, cytoplasm, infection, the microenvironment within the circulation granules, and organelles [144]. Platelets circulate throughout contains a variety of immune cytokines/chemokines. Some blood vessels during which they monitor the integrity of of these immune cytokines/chemokines have the capacity the vascular system. All functional platelet responses must to mobilize HPC to peripheral blood in response to the + + be tightly regulated to ensure that the formation of blood CD61 cells, such as megakary- invading pathogen. CD41 clots is of sufficient size to seal off the damaged area, while ocytes, normally account for 1% of the bone marrow but not disrupting blood flow to vital organs by causing vessel can change dramatically in certain diseases or infections occlusion [145–147]. With the observation that dengue and mobilize into the peripheral circulation. However, the viral antigens are associated with proplatelets [148, 149] presence of megakaryocytes in blood is a normal phys- or micromegakaryocytes [137, 150] in blood during acute iological occurrence [154]. Transport of megakaryocytes dengue virus infection (Figure 3), it is likely that a platelet in the blood is halted in the lungs, where the majority lineage parental cell, megakaryocytes, may be involved in shed their cytoplasm. Upon maturation via differentiation, the production of dengue virus during acute infection. In the process of releasing platelets is initiated. Cytokines, addition, platelets contain several key elements related to such as thrombopoietin, can orchestrate the formation of dengue virus infection, such as DC-SIGN [151]aswellas platelets, which are held within the internal membranes in complement and Fc receptor, which have been implicated the cytoplasm of megakaryocytes. Platelets are released via in virus uptake [152, 153]. It is also possible that a unique two proposed scenarios [155]; (a) megakaryocytes undergo receptor or coreceptor is required for viral binding and entry apoptosis to break up the platelets from demarcation of into platelets. However, this particular receptor or coreceptor membranes, and (b) formation of platelet pseudopodia may not be evenly distributed or allocated in platelets since ribbons (proplatelets), which are released into blood vessels 8 Advances in Virology 10 nm 10 nm 10 nm 10 nm 10 nm (a) 10 nm 10 nm 10 nm 10 nm 10 nm (b) Figure 3: Dengue antigens on platelets and its derivative cells. Isolated platelets were stained with dengue-specific antibody (3H5) and platelets-specific markers (CD41). (a) Dengue antigen was observed in platelets and proplatelets. (b) Dengue antigen was observed in a micromegakaryocyte. Green: platelet marker CD41; Red: dengue antigen; and Blue; DAPI for nucleus staining. Red bar, 10 μm. resulting in continuously release of platelets into the circula- Recently, a study profiling the gene expression by tion. In either scenario, each megakaryocyte can give rise to genome-scale transcriptional analysis in human primary 1000–3000 platelets [155], of which 2/3 of newly produced megakaryocytic cell reveals that interferon-response genes platelets remain in circulation while 1/3 is sequestered within are not induced or responsive to culture conditions or PMA the spleen. The remaining cell nucleus of the megakaryocyte, treatment [157, 158], suggesting that there is a possible which is covered with a very thin cytoplasmic membrane signaling defect in or impairment of interferon signaling in and is morphologically similar to the small lymphocytes megakaryocytes. Thus, bone marrow suppression observed [137, 156], then crosses the bone marrow barrier into the in dengue patients during the acute stage of infection, blood and is consumed in the lung by macrophage-mediated including reduction of megakaryocytes [61, 123, 125], may phagocytosis [156]. be due to direct disturbance or infection by dengue virus. Advances in Virology 9 10 While dengue virus or its antigens has been found in sev- eral tissues and cells [15, 18, 20, 67, 162]frompostmortem autopsy specimens and much important information has been generated; one thing has to be kept mind. By the time most of the patients are ill enough to be hospitalized, 10 they are at the end stage of the dengue virus infection, multiple organ lesions or failures have occurred, and the virus or viral antigens may be trapped in these tissues and/or engulfed by phagocytic cells. Furthermore, a large number of macrophages containing what appears to be incompletely 10 digested nuclear debris can be observed in autopsy specimens [62, 67, 161, 162], while the endothelial cells of the blood vessels look normal [67, 161, 162]. In addition, since dengue virus causes viremia in infected patients and the timing of the autopsy specimen collections are very critical, interpretation 10 of outcomes may be complicated by the constant blood 2 6 18 24 48 circulation in the body system when the patients are in Hours P.I. consciousness. As a whole, at present, it is impossible to decipher the actual meaning of viral antigens or RNA in Pellet cells observed in autopsy specimens. With the recent suitable Supernatant animal model, which is capable of recapitulating human Figure 4: Transient replication of dengue virus in platelets. Platelets dengue hemorrhages [64], the status of these cells may be were isolated from a healthy donor and experimentally infected with clarified in the near future. dengue virus serotype 2 (strain 16681) at an MOI of 0.01. RNA In summary, although many cell types including those was isolated from supernatants and pellets at indicated time and paired with ADE capacity may play a role in dengue subjected to real-time qRT-PCR for dengue viral RNA. virus infection and in the development of DHF/DSS, this paper by no means suggests that cells with an impaired interferon system are the cells accounting for dengue viremia Interestingly, damaged or degenerated megakaryocytes with homogenous hyalinized or reduced cytoplasms in bone in vivo. Instead, this current paper addresses the observed marrow biopsies from acute patients have been documented phenomena in the literature and summarizes the possible [61, 123, 135, 159, 160]. Additionally, autopsies performed scenarios. In addition, a new cell is suggested to have a role in in patients who died of acute dengue hemorrhagic fever DHF/DSS pathogenesis and warrants further investigation. in the early 1960s revealed an increase in the number of megakaryocytes in the capillaries of various organs [161]and 13. Conclusions the deposition of hyaline materials with large mononuclear cells of varying maturity in the germinal centers of the spleen + + A new lineage of cell—MEP or CD41 CD61 cells, such as [162]. megakaryocytes and/or platelets—is suggested for a potential Furthermore, a unique and previously neglected cell cell accounting for dengue viremia in vivo. The objective population, which has ultrastructural and morphological of the authors is to draw scientific attention to the highly appearance similar to that of micromegakaryocytes [137, fragile cell with unusual biological properties in acute 150]and apossiblesourceofdengue viremia[22, 123], dengue virus infection. After all, hemostatic defects in DHF were seen in circulation during the acute phase of infection appear to be a major clinical finding. Our aim is to foster [129, 160], though the likely phenotypes of these neglected + + more detailed investigations of the MEP or CD41 CD61 cells are not well defined. cells in specimens collected from acute dengue patients, In addition, bone marrow aspiration studies show that which conceivably will not only provide a piece of valuable erythroid cells are diminished transiently in all cases of information of the mechanisms associated with DHF/DSS, dengue, some with an arrest of maturation [124, 126]. but will also pave a new way on the formulation of effective However, due to the long half-life of red blood cells candidate vaccines or antiviral drugs development. in circulation, the transiently halted erythropoiesis does not cause severe anemia in dengue patients. This line of evidence suggests a possibility of a transient involvement of Acknowledgments megakaryocyte-erythroid progenitor (MEP) cells in dengue virus infection. Whether direct infection of MEP cells or The authors thank the clinical staffs in the Department of megakaryocytes by dengue virus can induce an aberrational Pediatrics, Siriraj Hospital for technical assistance in patient transcriptional event, such as a disturbance of nucleic acid blood collection. The authors appreciate Kristina Bargeron synthesis, resulting in the transiently halted erythropoiesis or Clark and David Clark for their kindness of editing the increased production of immature megakaryocytes and atyp- paper as well as the kind and knowledgeable assistance of ical lymphocytes circulating in the blood remains unclear Dr. Hong Yi from Electron Microscopy Core Facility of the and warrants more exploration. Emory University School of Medicine. The paper is partially Viral RNA (copies/mL) 10 Advances in Virology supported by U19 Pilot Project Funds (RFA-AI-02-042), human lymphoblastoid cells and subpopulations of human peripheral leukocytes,” Journal of Immunology, vol. 117, no. NIH/SERCEB, and Emory URC grants. 3, pp. 953–961, 1976. [18] S. J. Balsitis, J. Coloma, G. Castro et al., “Tropism of dengue virus in mice and humans defined by viral nonstructural References protein 3-specific immunostaining,” The American Journal [1] G.Clark,D.Gubler, andJ.DengueFever, CDC Traveler’s of Tropical Medicine & Hygiene, vol. 80, no. 3, pp. 416–424, Information on Dengue Fever, Centers for Disease Control, 2009. Atlanta, Ga, USA. [19] A. P. Durbin, M. J. Vargas, K. Wanionek et al., “Phenotyping [2] M.G.Guzman, ´ G. Kour´ı, M. D´ıaz et al., “Dengue, one of the of peripheral blood mononuclear cells during acute dengue great emerging health challenges of the 21st century,” Expert illness demonstrates infection and increased activation of Review of Vaccines, vol. 3, no. 5, pp. 511–520, 2004. monocytes in severe cases compared to classic dengue fever,” [3] WHO, Prevention and Control of Dengue and Dengue Haem- Virology, vol. 376, no. 2, pp. 429–435, 2008. orrhagic Fever, WHO, SEARO, 1999. [20] K. Jessie, M. Y. Fong, S. Devi, S. K. Lam, and K. T. Wong, [4] S. B. Halstead, “Dengue,” The Lancet, vol. 370, no. 9599, pp. “Localization of dengue virus in naturally infected human 1644–1652, 2007. tissues, by immunohistochemistry and in situ hybridization,” [5] NIAID, Dengue Fever, 2005. Journal of Infectious Diseases, vol. 189, no. 8, pp. 1411–1418, [6] D. M. Morens and A. S. Fauci, “Dengue and hemorrhagic fever: a potential threat to public health in the United States,” [21] R. M. Zellweger, T. R. Prestwood, and S. Shresta, “Enhanced Journal of the American Medical Association, vol. 299, no. 2, infection of liver sinusoidal endothelial cells in a mouse pp. 214–216, 2008. model of antibody-induced severe dengue disease,” Cell Host [7] T.J.Chambers, C. S. Hahn, R. Galler, andC.M.Rice, “Fla- and Microbe, vol. 7, no. 2, pp. 128–139, 2010. vivirus genome organization, expression, and replication,” [22] R. M. Scott, A. Nisalak, and U. Cheamudon, “Isolation of Annual Review of Microbiology, vol. 44, pp. 649–688, 1990. dengue viruses from peripheral blood leukocytes of patients [8] N. Sangkawibha, S. Rojanasuphot, and S. Ahandrik, “Risk with hemorrhagic fever,” Journal of Infectious Diseases, vol. factors in dengue shock syndrome: a prospective epidemi- 141, no. 1, pp. 1–6, 1980. ologic study in Rayong, Thailand. I. The 1980 outbreak,” [23] S. B. Halstead, E. J. O’Rourke, and A. C. Allison, “Dengue American Journal of Epidemiology, vol. 120, no. 5, pp. 653– viruses and mononuclear phagocytes. II. Identity of blood 669, 1984. and tissue leukocytes supporting in vitro infection,” Journal [9] B. S. Andrews, A. N. Theofilopoulos, and C. J. Peters, of Experimental Medicine, vol. 146, no. 1, pp. 218–229, 1977. “Replication of dengue and junin viruses in cultured rabbit [24] A. D. King, A. Nisalak, S. Kalayanrooj et al., “B cells are the and human endothelial cells,” Infection and Immunity, vol. principal circulating mononuclear cells infected by dengue 20, no. 3, pp. 776–781, 1978. virus,” Southeast Asian Journal of Tropical Medicine and Public [10] M. T. Arevalo ´ , P. J. Simpson-Haidaris, Z. Kou, J. J. Health, vol. 30, no. 4, pp. 718–728, 1999. Schlesinger, and X. Jin, “Primary human endothelial cells [25] R. Scott, A. Nisalak, and U. Cheam-u-Dom, “A preliminary support direct but not antibody-dependent enhancement of report on the isolation of viruses from the platelets and dengue viral infection,” Journal of Medical Virology, vol. 81, leukocytes of dengue patients,” Asian Journal of Infectious no. 3, pp. 519–528, 2009. Diseases, vol. 2, no. 1, pp. 95–97, 1978. [11] A. Azizan, K. Fitzpatrick, A. Signorovitz et al., “Profile of [26] S.-J. L. Wu, G. Grouard-Vogel, W. Sun et al., “Human time-dependent VEGF upregulation in human pulmonary skin Langerhans cells are targets of dengue virus infection,” endothelial cells, HPMEC-ST1.6R infected with DENV-1, - Nature Medicine, vol. 6, no. 7, pp. 816–820, 2000. 2, -3, and -4 viruses,” Virology Journal, vol. 6, article 49, 2009. [27] J. L. Kyle, P. R. Beatty, and E. Harris, “Dengue virus infects [12] C. Cabello-Gutier ´ rez, M. E. Manjarrez-Zavala, A. Huerta- macrophages and dendritic cells in a mouse model of Zepeda et al., “Modification of the cytoprotective protein C infection,” Journal of Infectious Diseases, vol. 195, no. 12, pp. pathway during Dengue virus infection of human endothelial 1808–1817, 2007. vascular cells,” Thrombosis and Haemostasis, vol. 101, no. 5, [28] M. Marovich, G. Grouard-Vogel, M. Louder, et al., “Human pp. 916–928, 2009. dendritic cells as targets of dengue virus infection,” Journal of [13] I. Kurane, D. Hebblewaite, W. E. Brandt, and F. A. Ennis, Investigative Dermatology Symposium Proceedings, vol. 6, no. “Lysis of dengue virus-infected cells by natural cell-mediated 3, pp. 219–224, 2001. cytotoxicity and antibody-dependent cell-mediated cytotox- [29] J. L. Miller,B.J.M.DeWet,L.Martinez-Pomaresetal., icity,” Journal of Virology, vol. 52, no. 1, pp. 223–230, 1984. “The mannose receptor mediates dengue virus infection of [14] I. Kurane and F. A. Ennis, “Production of interferon alpha by macrophages,” PLoS Pathogens, vol. 4, article e17, 2008. dengue virus-infected human monocytes,” Journal of General [30] Z. D. Nightingale, C. Patkar, and A. L. Rothman, “Viral Virology, vol. 69, part 2, pp. 445–449, 1988. replication and paracrine effects result in distinct, functional [15] I. Kurane, U. Kontny, J. Janus, and F. A. Ennis, “Dengue- responses of dendritic cells following infection with dengue 2 virus infection of human mononuclear cell lines and 2 virus,” Journal of Leukocyte Biology, vol. 84, no. 4, pp. 1028– establishment of persistent infections,” Archives of Virology, 1038, 2008. vol. 110, no. 1-2, pp. 91–101, 1990. [31] P. Sun, S. Fernandez, M. A. Marovich et al., “Functional [16] S. Sriurairatna, N. Bhamarapravati, A. R. Diwan, and S. B. characterization of ex vivo blood myeloid and plasmacytoid Halstead, “Ultrastructural studies on dengue virus infection dendritic cells after infection with dengue virus,” Virology, of human lymphoblasts,” Infection and Immunity, vol. 20, no. vol. 383, no. 2, pp. 207–215, 2009. 1, pp. 173–179, 1978. [32] B. Tassaneetrithep, T. H. Burgess, A. Granelli-Piperno et al., [17] A. N. Theofilopoulos,W.E.Brandt,P.K.Russell,and F. T. Dixon, “Replication of dengue 2 virus in cultured “DC-SIGN (CD209) mediates dengue virus infection of Advances in Virology 11 human dendritic cells,” Journal of Experimental Medicine, vol. [46] R. B. Griffiths and R. M. Gordon, “An apparatus which 197, no. 7, pp. 823–829, 2003. enables the process of feeding by mosquitoes to be observed in the tissues of a live rodent; together with an account of [33] J. P. Wang,P.Liu,E.Latz, D. T. Golenbock, R. W. Finberg, the ejection of saliva and its significance in Malaria,” Annals and D. H. Libraty, “Flavivirus activation of plasmacytoid of Tropical Medicine and Parasitology, vol. 46, no. 4, pp. 311– dendritic cells delineates key elements of TLR7 signaling 319, 1952. beyond endosomal recognition,” Journal of Immunology, vol. 177, no. 10, pp. 7114–7121, 2006. [47] F. J. O’Rourke, “Observations on pool and capillary feeding in aedes aegypt,” Nature, vol. 177, no. 4519, pp. 1087–1088, [34] W.-H. Kwan, E. Navarro-Sanchez, H. Dumortier et al., “Dermal-type macrophages expressing CD209/DC-SIGN show inherent resistance to dengue virus growth,” PLoS [48] T. L. Daniel and J. G. Kingsolver, “Feeding strategy and the Neglected Tropical Diseases, vol. 2, no. 10, article e311, 2008. mechanics of blood sucking in insects,” Journal of Theoretical [35] A. Y. Limon-Flores, M. Perez-Tapia, I. Estrada-Garcia et Biology, vol. 105, no. 4, pp. 661–677, 1983. al., “Dengue virus inoculation to human skin explants: an [49] M. K. Ramasubramanian, O. M. Barham, and V. Swami- effective approach to assess in situ the early infection and the nathan, “Mechanics of a mosquito bite with applications to effects on cutaneous dendritic cells,” International Journal of microneedle design,” Bioinspiration and Biomimetics, vol. 3, Experimental Pathology, vol. 86, no. 5, pp. 323–334, 2005. no. 4, Article ID 046001, 2008. [36] S. Taweechaisupapong, S. Sriurairatana, S. Angsubhakorn, S. [50] L. M. Styer, K. A. Kent, R. G. Albright, C. J. Bennett, L. Yoksan, and N. Bhamarapravati, “In vivo and in vitro studies D. Kramer, and K. A. Bernard, “Mosquitoes inoculate high on the morphological change in the monkey epidermal doses of West Nile virus as they probe and feed on live hosts,” Langerhans cells following exposure to dengue 2 (16681) PLoS Pathogens, vol. 3, no. 9, pp. 1262–1270, 2007. virus,” Southeast Asian Journal of Tropical Medicine and Public [51] M. M. Davis, “A Prescription for Human Immunology,” Health, vol. 27, no. 4, pp. 664–672, 1996. Immunity, vol. 29, no. 6, pp. 835–838, 2008. [37] W. Jampangern, K. Vongthoung, A. Jittmittraphap et al., [52] J. Mestas and C. C. W. Hughes, “Of Mice and Not Men: dif- “Characterization of atypical lymphocytes and immunophe- ferences between mouse and human immunology,” Journal of notypes of lymphocytes in patients with dengue virus Immunology, vol. 172, no. 5, pp. 2731–2738, 2004. infection,” Asian Pacific Journal of Allergy and Immunology, [53] K. Yang, A. Puel, S. Zhang et al., “Human TLR-7-, -8-, and vol. 25, no. 1, pp. 27–36, 2007. -9-mediated induction of IFN-alpha/beta and -lambda Is [38] S. Boonpucknavig, C. Lohachitranond, and S. Nimmanitya, IRAK-4 dependent and redundant for protective immunity “The pattern and nature of the lymphocyte population to viruses,” Immunity, vol. 23, no. 5, pp. 465–478, 2005. response in dengue hemorrhagic fever,” The American Jour- [54] E. Boilard, P. A. Nigrovic, K. Larabee et al., “Platelets nal of Tropical Medicine & Hygiene, vol. 28, no. 5, pp. 885– amplify inflammation in arthritis via collagen-dependent 889, 1979. microparticle production,” Science, vol. 327, no. 5965, pp. [39] R. A. Wells, R. Scott McN., and K. Pavanand, “Kinetics of 580–583, 2010. peripheral blood leukocyte alterations in Thai children with [55] R. W. Faint, “Platelet-neutrophil interactions: their signifi- dengue hemorrhagic fever,” Infection and Immunity, vol. 28, cance,” Blood Reviews, vol. 6, no. 2, pp. 83–91, 1992. no. 2, pp. 428–433, 1980. [56] M. P. Gawaz, S. K. Mujais, B. Schmidt, and H. J. Gurland, [40] L. A. J. O’Neill, “Therapeutic targeting of Toll-like receptors “Platelet-leukocyte aggregation during hemodialysis,” Kidney for inflammatory and infectious diseases,” Current Opinion International, vol. 46, no. 2, pp. 489–495, 1994. in Pharmacology, vol. 3, no. 4, pp. 396–403, 2003. [57] S. Reuter and D. Lang, “Life span of monocytes and platelets: [41] N. Bechetoille, V. Andre, ´ J. Valladeau, E. Perrier, and C. importance of interactions,” Frontiers in Bioscience, vol. 14, Dezutter-Dambuyant, “Mixed Langerhans cell and intersti- pp. 2432–2447, 2009. tial/dermal dendritic cell subsets emanating from mono- [58] H. M. Rinder,J.L.Bonan,C.S.Rinder,K.A.Ault, and cytes in Th2-mediated inflammatory conditions respond B. R. Smith, “Activated and unactivated platelet adhesion to differently to proinflammatory stimuli,” Journal of Leukocyte monocytes and neutrophils,” Blood, vol. 78, no. 7, pp. 1760– Biology, vol. 80, no. 1, pp. 45–58, 2006. 1769, 1991. [42] L. De Witte, A. Nabatov, M. Pion et al., “Langerin is a natural [59] G. Bazzoni, E. Dejana, and A. Del Maschio, “Platelet- barrier to HIV-1 transmission by Langerhans cells,” Nature neutrophil interactions. Possible relevance in the pathogene- Medicine, vol. 13, no. 3, pp. 367–371, 2007. sis of thrombosis and inflammation,” Haematologica, vol. 76, [43] L. de Witte, A. Nabatov, and T. B. H. Geijtenbeek, “Distinct no. 6, pp. 491–499, 1991. roles for DC-SIGN+-dendritic cells and Langerhans cells in [60] B. K. Aikat, “Pathology of mosquito-borne haemorrhagic HIV-1 transmission,” Trends in Molecular Medicine, vol. 14, fever in the Calcutta outbreak,” Bull World Health Organ, vol. no. 1, pp. 12–19, 2008. 35, pp. 48–49, 1966. [44] K. Nagao, F. Ginhoux, W. W. Leitner et al., “Murine [61] E. R. Nelson, H. R. Bierman, and R. Chulajata, “Hematologic epidermal Langerhans cells and langerin-expressing dermal dendritic cells are unrelated and exhibit distinct functions,” findings in the 1960 hemorrhagic fever epidemic (dengue) in Thailand,” The American Journal of Tropical Medicine & Proceedings of the National Academy of Sciences of the United States of America, vol. 106, no. 9, pp. 3312–3317, 2009. Hygiene, vol. 13, pp. 642–649, 1964. [45] R. M. Gordon and W. H. R. Lumsden, “A study of the [62] E. R. Nelson, H. R. Bierman, and R. Chulajata, “Hemato- behaviour of the mouth-parts of mosquitoes when taking up logic phagocytosis in postmortem bone marrows of dengue blood from living tissues; together with some observations hemorrhagic fever. (Hematologic phagocytosis in Thai hem- on the ingestion of microfilariae,” Annals of Tropical Medicine orrhagic fever),” American Journal of the Medical Sciences, vol. and Parasitology, vol. 33, pp. 259–278, 1939. 252, no. 1, pp. 68–74, 1966. 12 Advances in Virology [63] N. J. Marchette, S. B. Halstead, and W. A. Falkler Jr., “Studies pre-existing specific antibodies,” Journal of Medical Virology, on the pathogenesis of dengue infection in monkeys. III. vol. 54, no. 3, pp. 210–218, 1998. Sequential distribution of virus in primary and heterologous [78] S. Honda, M. Saito, E. M. Dimaano et al., “Increased phago- infections,” Journal of Infectious Diseases, vol. 128, no. 1, pp. cytosis of platelets from patients with secondary dengue virus 23–30, 1973. infection by human macrophages,” The American Journal of Tropical Medicine & Hygiene, vol. 80, no. 5, pp. 841–845, [64] N. Onlamoon, S. Noisakran, H.-M. Hsiao et al., “Dengue virus—induced hemorrhage in a nonhuman primate model,” Blood, vol. 115, no. 9, pp. 1823–1834, 2010. [79] P. Marianneau, A.-M. Steffan, C. Royer et al., “Infection of primary cultures of human Kupffer cells by dengue virus: no [65] N. J. Marchette, J. S. Sung Chow, and S. B. Halstead, “Dengue viral progeny synthesis, but cytokine production is evident,” virus replication in cultures of peripheral blood leukocytes Journal of Virology, vol. 73, no. 6, pp. 5201–5206, 1999. during the course of Dengue haemorrhagic fever,” Southeast [80] J. A. Mosquera, J. P. Hernandez, N. Valero, L. M. Espina, and Asian Journal of Tropical Medicine and Public Health, vol. 6, G. J. Anez, ˜ “Ultrastructural studies on dengue virus type 2 no. 3, pp. 316–321, 1975. infection of cultured human monocytes,” Virology Journal, [66] N. J. Marchette, S. B. Halstead, and J. S. Chow, “Replication vol. 2, article 26, 2005. of dengue viruses in cultures of peripheral blood leukocytes [81] K. Fink, C. Ng, C. Nkenfou, S. G. Vasudevan, N. Van from dengue immune rhesus monkeys,” Journal of Infectious Rooijen, and W. Schul, “Depletion of macrophages in mice Diseases, vol. 133, no. 3, pp. 274–282, 1976. results in higher dengue virus titers and highlights the [67] N. Bhamarapravati, P. Tuchinda, and V. Boonyapaknavik, role of macrophages for virus control,” European Journal of “Pathology of Thailand haemorrhagic fever: a study of 100 Immunology, vol. 39, no. 10, pp. 2809–2821, 2009. autopsy cases,” Annals of Tropical Medicine and Parasitology, [82] A. E. Calvert, C. Y.-H. Huang, R. M. Kinney, and J. T. Roehrig, vol. 61, no. 4, pp. 500–510, 1967. “Non-structural proteins of dengue 2 virus offer limited [68] F. C. de Macedo,A.F.Nicol, L. D. Cooper,M.Yearsley,A. protection to interferon-deficient mice after dengue 2 virus R. Cordovil Pires, andG.J.Nuovo,“Histologic, viral, and challenge,” Journal of General Virology, vol. 87, no. 2, pp. 339– molecular correlates of dengue fever infection of the liver 346, 2006. using highly sensitive immunohistochemistry,” Diagnostic [83] M. S. Diamond, T. G. Roberts, D. Edgil, B. Lu, J. Ernst, and E. Molecular Pathology, vol. 15, no. 4, pp. 223–228, 2006. Harris, “Modulation of dengue virus infection in human cells [69] S. B. Halstead and E. J. O’Rourke, “Antibody enhanced by alpha, beta, and gamma interferons,” Journal of Virology, dengue virus infection in primate leukocytes,” Nature, vol. vol. 74, no. 11, pp. 4957–4966, 2000. 265, no. 5596, pp. 739–741, 1977. [84] M. O. Diaz, S. Ziemin, M. M. Le Beau et al., “Homozygous [70] S. B. Halstead, “Observations related to pathogensis of deletion of the α-and β1-interferon genes in human dengue hemorrhagic fever. VI. Hypotheses and discussion,” leukemia and derived cell lines,” Proceedings of the National Yale Journal of Biology and Medicine, vol. 42, no. 5, pp. 350– Academy of Sciences of the United States of America, vol. 85, 362, 1970. no. 14, pp. 5259–5263, 1988. [71] A. C. Eaves, J. D. Cashman, and L. A. Gaboury, “Unregulated [85] M. O. Diaz, C. M. Rubin, A. Harden et al., “Deletions of proliferation of primitive chronic myeloid leukemia pro- interferon genes in acute lymphoblastic leukemia,” The New genitors in the presence of normal marrow adherent cells,” England Journal of Medicine, vol. 322, no. 2, pp. 77–82, 1990. Proceedings of the National Academy of Sciences of the United [86] S. Einhorn, D. Grander, O. Bjork, K. Brondum-Nielsen, States of America, vol. 83, no. 14, pp. 5306–5310, 1986. andS.Soderhall,“Deletion of falpha-, beta-, andomega- [72] S. Blackley, Z. Kou, H. Chen et al., “Primary Human splenic interferon genes in malignant cells from children with acute macrophages, but not T or B cells, are the principal target lymphocytic leukemia,” Cancer Research, vol. 50, no. 24, pp. cells for dengue virus infection in vitro,” Journal of Virology, 7781–7785, 1990. vol. 81, no. 24, pp. 13325–13334, 2007. [87] C. D. James, J. He,E.Carlbom,M.Nordenskjold,W.K. [73] K.-J. Huang, Y.-C. Yang, Y.-S. Lin et al., “The dual-specific Cavenee, and V. P. Collins, “Chromosome 9 deletion map- binding of dengue virus and target cells for the antibody- ping reveals interferon α and interferon β-1 gene deletions dependent enhancement of dengue virus infection,” Journal in human glial tumors,” Cancer Research, vol. 51, no. 6, pp. of Immunology, vol. 176, no. 5, pp. 2825–2832, 2006. 1684–1688, 1991. [74] S. C. Kliks, A. Nisalak, W. E. Brandt, L. Wahl, and D. S. Burke, [88] J. Miyakoshi, K. D. Dobler, J. Allalunis-Turner et al., “Absence “Antibody-dependent enhancement of dengue virus growth of IFNA and IFNB genes from human malignant glioma in human monocytes as a risk factor for dengue hemorrhagic cell lines and lack of correlation with cellular sensitivity to fever,” The American Journal of Tropical Medicine & Hygiene, interferons,” Cancer Research, vol. 50, no. 2, pp. 278–283, vol. 40, no. 4, pp. 444–451, 1989. [75] L. M. Espina, N. J. Valero, J. M. Hernandez, ´ and J. A. [89] J. Fink, F. Gu, L. Ling et al., “Host gene expression profiling Mosquera, “Increased apoptosis and expression of tumor of dengue virus infection in cell lines and patients,” PLoS necrosis factor-α caused by infection of cultured human Neglected Tropical Diseases, vol. 1, no. 2, article e86, 2007. monocytes with dengue virus,” The American Journal of [90] I. Kurane, J. Janus, and F. A. Ennis, “Dengue virus infection Tropical Medicine & Hygiene, vol. 68, no. 1, pp. 48–53, 2003. of human skin fibroblasts in vitro production of IFN-β,IL- [76] T. Hase, P. L. Summers, and K. H. Eckels, “Flavivirus entry 6and GM-CSF,” Archives of Virology, vol. 124, no. 1-2, pp. into cultured mosquito cells and human peripheral blood 21–30, 1992. monocytes,” Archives of Virology, vol. 104, no. 1-2, pp. 129– [91] I. Kurane, B. L. Innis, S. Nimmannitya, A. Nisalak, A. Meager, 143, 1989. and F. A. Ennis, “High levels of interferon alpha in the sera of [77] D. Hober, T. L. Nguyen, L. Shen et al., “Tumor necrosis factor children with dengue virus infection,” The American Journal alpha levels in plasma and whole-blood culture in dengue- of Tropical Medicine & Hygiene, vol. 48, no. 2, pp. 222–229, infected patients: relationship between virus detection and 1993. Advances in Virology 13 [92] C. A. Sariol, J.L. Muno ˜ z-Jordan, K. Abel et al., “Transcrip- Journal of Tropical Medicine & Hygiene,vol. 52, no.5,pp. tional activation of interferon-stimulated genes but not of 468–476, 1995. cytokine genes after primary infection of rhesus macaques [110] S. B. Halstead, “In vivo enhancement of Dengue virus infec- with dengue virus type 1,” Clinical and Vaccine Immunology, tion in rhesus monkeys by passively transferred antibody,” vol. 14, no. 6, pp. 756–766, 2007. Journal of Infectious Diseases, vol. 140, no. 4, pp. 527–533, [93] D. A. Bente and R. Rico-Hesse, “Models of dengue virus infection,” Drug Discovery Today: Disease Models, vol. 3, no. [111] N. J. Marchette and S. B. Halstead, “Immunopathogenesis 1, pp. 97–103, 2006. of dengue infection in the rhesus monkey,” Transplantation [94] L. E. Yauch and S. Shresta, “Mouse models of dengue virus Proceedings, vol. 6, no. 2, pp. 197–201, 1974. infection and disease,” Antiviral Research, vol. 80, no. 2, pp. [112] L. Rosen, “Experimental infection of New World monkeys 87–93, 2008. with dengue and yellow fever viruses,” The American Society [95] H.-C. Chen, S.-Y. Lai, J.-M. Sung et al., “Lymphocyte acti- of Tropical Medicine & Hygiene, vol. 7, no. 4, pp. 406–410, vation and hepatic cellular infiltration in immunocompetent mice infected by dengue virus,” JournalofMedical Virology, [113] A. Rudnick, N. J. Marchette, and R. Garcia, “Possible jungle vol. 73, no. 3, pp. 419–431, 2004. dengue—recent studies and hypotheses,” Japanese Journal of [96] M. V. Paes,A.T.Pinhao, D. F. Barreto et al., “Liver injury and Medical Science and Biology, vol. 20, pp. 69–74, 1967. viremia in mice infected with dengue-2 virus,” Virology, vol. [114] J. S. Simmons, J. H. St. John, and F. H. K. Reynolds, “Exper- 338, no. 2, pp. 236–246, 2005. imental studies of dengue,” Philippine Journal of Science, vol. [97] J. R. Paul, J. L. Melnick, and A. B. Sabin, “Experimental 44, pp. 1–252, 1931. attempts to transmit phlebotomus and dengue fevers to [115] R. H. Whitehead, V. Chaicumpa, L. C. Olson, and P. K. chimpanzees,” Proceedings of The Society for Experimental Russell, “Sequential dengue virus infections in the white- Biology and Medicine, vol. 68, no. 1, pp. 193–198, 1948. handed gibbon (Hylobates lar),” The American Journal of [98] A. B. Sabin, “Research on dengue during World War II,” The Tropical Medicine & Hygiene, vol. 19, no. 1, pp. 94–102, 1970. American Journal of Tropical Medicine & Hygiene, vol. 1, no. [116] F. Guirakhoo, K. Pugachev, J. Arroyo et al., “Viremia and 1, pp. 30–50, 1952. [99] S.-T. Chen, Y.-L. Lin, M.-T. Huang et al., “CLEC5A is critical immunogenicity in nonhuman primates of a tetravalent yel- low fever-dengue chimeric vaccine: genetic reconstructions, for dengue-virus-induced lethal disease,” Nature, vol. 453, dose adjustment, and antibody responses against wild-type no. 7195, pp. 672–676, 2008. dengue virus isolates,” Virology, vol. 298, no. 1, pp. 146–159, [100] Y.-H. Huang, H.-Y. Lei, H.-S. Liu, Y.-S. Lin, C.-C. Liu, and T.- M. Yeh, “Dengue virus infects human endothelial cells and induces IL-6 and IL-8 production,” The American Journal [117] B. Guy, V. Barban, N. Mantel et al., “Evaluation of interfer- of Tropical Medicine & Hygiene, vol. 63, no. 1-2, pp. 71–75, ences between dengue vaccine serotypes in a monkey model,” The American Journal of Tropical Medicine & Hygiene, vol. 80, [101] A. J. Johnson and J. T. Roehrig, “New mouse model for no. 2, pp. 302–311, 2009. dengue virus vaccine testing,” Journal of Virology, vol. 73, no. [118] P. Koraka, S. Benton, G. V. Amerongen, K. J. Stittelaar, and 1, pp. 783–786, 1999. A. D. M. E. Osterhaus, “Characterization of humoral and [102] S. Shresta, K. L. Sharar, D. M. Prigozhin, P. R. Beatty, cellular immune responses in cynomolgus macaques upon and E. Harris, “Murine model for dengue virus-induced primary and subsequent heterologous infections with dengue lethal disease with increased vascular permeability,” Journal viruses,” Microbes and Infection, vol. 9, no. 8, pp. 940–946, of Virology, vol. 80, no. 20, pp. 10208–10217, 2006. [103] J. An, J. Kimura-Kuroda, Y. Hirabayashi, and K. Yasui, [119] J. Velzing, J. Groen, M. T. Drouet et al., “Induction of pro- “Development of a novel mouse model for dengue virus tective immunity against dengue virus type 2: comparison infection,” Virology, vol. 263, no. 1, pp. 70–77, 1999. of candidate live attenuated and recombinant vaccines,” [104] D. A. Bente, M. W. Melkus, J. V. Garcia, and R. Rico-Hesse, Vaccine, vol. 17, no. 11-12, pp. 1312–1320, 1999. “Dengue fever in humanized NOD/SCID mice,” Journal of [120] J. Stasney and G. M. Higgins, “Bone marrow in the monkey Virology, vol. 79, no. 21, pp. 13797–13799, 2005. (macacus rhesus),” The Anatomical Record,vol. 67, no.2,pp. [105] J. E. Blaney Jr., D. H. Johnson, G. G. Manipon et al., “Genetic 219–231, 1973. basis of attenuation of dengue virus type 4 small plaque [121] L. Wills and A. Stewart, “Experimental Anaemia in monkeys, mutants with restricted replication in suckling mice and in with special reference to macrocytic nutritional anaemia,” SCID mice transplanted with human liver cells,” Virology, British Journal of Experimental Pathology, vol. 16, pp. 444– vol. 300, no. 1, pp. 125–139, 2002. 453, 1935. [106] J. G. Kuruvilla, R. M. Troyer, S. Devi, and R. Akkina, “Dengue [122] T. Kushida, M. Inaba, K. Ikebukuro et al., “Comparison of virus infection and immune response in humanized RAG2-/- bone marrow cells harvested from various bones of cynomol- γc-/- (RAG-hu) mice,” Virology, vol. 369, no. 1, pp. 143–152, gusmonkeys at variousagesbyperfusion or aspiration methods: a preclinical study for human BMT,” Stem Cells, vol. [107] Y.-L. Lin, C.-L. Liao, L.-K. Chen et al., “Study of dengue virus 20, no. 2, pp. 155–162, 2002. infection in SCID mice engrafted with human K562 cells,” [123] H. R. Bierman and E. R. Nelson, “Hematodepressive virus Journal of Virology, vol. 72, no. 12, pp. 9729–9737, 1998. diseases of Thailand,” Annals of Internal Medicine, vol. 62, pp. [108] J. Mota and R. Rico-Hesse, “Humanized mice show clinical 867–884, 1965. signs of dengue fever according to infecting virus genotype,” Journal of Virology, vol. 83, no. 17, pp. 8638–8645, 2009. [124] S. Na-Nakorn, A. Suingdumrong, S. Pootrakul, and N. [109] S.-J. L. Wu, C. G. Hayes, D. R. Dubois et al., “Evaluation Bhamarapravati, “Bone-marrow studies in Thai haemor- of the severe combined immunodeficient (SCID) mouse as rhagic fever,” Bull World Health Organ, vol. 35, no. 17, pp. an animal model for dengue viral infection,” The American 54–55, 1966. 14 Advances in Virology [125] E. R. Nelson and H. R. Bierman, “Dengue fever: a thrombo- [142] K. Jurk and B. E. Kehrel, “Platelets: physiology and biochem- cytopenic disease?” Journal of the American Medical Associa- istry,” Seminars in Thrombosis and Hemostasis,vol. 31, no.4, tion, vol. 190, pp. 99–103, 1964. pp. 381–392, 2005. [126] E. R. Nelson, S. Tuchinda, H. R. Bierman, and R. Chulajata, [143] Z. M. Ruggeri, “Platelets in atherothrombosis,” Nature “Haematology of Thai haemorrhagic fever (dengue),” Bull Medicine, vol. 8, no. 11, pp. 1227–1234, 2002. World Health Organ, vol. 35, pp. 43–44, 1966. [144] J. H. Hartwig, “The platelet: form and function,” Seminars in [127] K. Oishi, M. Saito, C. A. Mapua, and F. F. Natividad, “Dengue Hematology, vol. 43, no. 1, pp. S94–S100, 2006. illness: clinical features and pathogenesis,” Journal of Infection [145] R. K. Andrews and M. C. Berndt, “Platelet physiology and and Chemotherapy, vol. 13, no. 3, pp. 125–133, 2007. thrombosis,” Thrombosis Research, vol. 114, no. 5-6, pp. 447– [128] K. I. Schexneider and E. A. Reedy, “Thrombocytopenia in 453, 2004. dengue fever,” Current Hematology Reports,vol. 4, no.2,pp. [146] K. Kaushansky, “Historical review: megakaryopoiesis and 145–148, 2005. thrombopoiesis,” Blood, vol. 111, no. 3, pp. 981–986, 2008. [129] T. Srichaikul and S. Nimmannitya, “Haematology in dengue [147] F. Rendu and B. Brohard-Bohn, “The platelet release reac- anddenguehaemorrhagicfever,” Bailliere’s Best Practice and tion: granules’ constituents, secretion and functions,” Research in Clinical Haematology, vol. 13, no. 2, pp. 261–276, Platelets, vol. 12, no. 5, pp. 261–273, 2001. [148] J. E. Italiano Jr., P. Lecine, R. A. Shivdasani, and J. H. [130] M. Saito, K. Oishi, S. Inoue et al., “Association of increased Hartwig, “Blood platelets are assembled principally at the platelet-associated immunoglobulins with thrombocytope- ends of proplatelet processes produced by differentiated nia and the severity of disease in secondary dengue virus megakaryocytes,” Journal of Cell Biology, vol. 147, no. 6, pp. infections,” Clinical and Experimental Immunology, vol. 138, 1299–1312, 1999. no. 2, pp. 299–303, 2004. [149] S. R. Patel, J. H. Hartwig, and J. E. Italiano Jr., “The biogenesis [131] S. Noisakran and C. P. Guey, “Alternate hypothesis on the of platelets from megakaryocyte proplatelets,” Journal of pathogenesis of dengue hemorrhagic fever (DHF)/dengue Clinical Investigation, vol. 115, no. 12, pp. 3348–3354, 2005. shock syndrome (DSS) in dengue virus infection,” Experi- [150] W. N. Erber, A. Jacobs, D. G. Oscier, A. M. O’Hea, and D. Y. mental Biology and Medicine, vol. 233, no. 4, pp. 401–408, Mason, “Circulating micromegakaryocytes in myelodyspla- sia,” Journal of Clinical Pathology, vol. 40, no. 11, pp. 1349– [132] S. Noisakran, K. Chokephaibulkit, P. Songprakhon et al., “A 1352, 1987. re-evaluation of the mechanisms leading to dengue hemor- [151] S. Boukour, J.-M. Masse, ´ L. Benit, ´ A. Dubart-Kupperschmitt, rhagic fever,” Annals of the New York Academy of Sciences, vol. and E. M. Cramer, “Lentivirus degradation and DC-SIGN 1171, supplement 1, pp. E24–E35, 2009. expression by human platelets and megakaryocytes,” Journal [133] S. Noisakran, R. V. Gibbons, P. Songprakhon et al., “Detec- of Thrombosis and Haemostasis, vol. 4, no. 2, pp. 426–435, tion of dengue virus in platelets isolated from dengue patients,” Southeast Asian Journal of Tropical Medicine and [152] C. L. Anderson, G. W. Chacko, J. M. Osborne, and J. T. Public Health, vol. 40, no. 2, pp. 253–262, 2009. Brandt, “The Fc receptor for immunoglobulin G (FcγRII) [134] R. Flaumenhaft, J. R. Dilks, J. Richardson et al., “Meg- on human platelets,” Seminars in Thrombosis and Hemostasis, akaryocyte-derived microparticles: direct visualization and vol. 21, no. 1, pp. 1–9, 1995. distinction from platelet-derived microparticles,” Blood, vol. [153] C. Skoglund, J. Wettero, ¨ T. Skogh, C. Sjowal ¨ l, P. Tengvall, and 113, no. 5, pp. 1112–1121, 2009. T. Bengtsson, “C-reactive protein and C1q regulate platelet [135] N. Bhamarapravati, V. Boonyapaknavik, and P. Nimsombu- adhesion and activation on adsorbed immunoglobulin G and rana, “Pathology of Thai haemorrhagic fever: an autopsy albumin,” Immunology and Cell Biology, vol. 86, no. 5, pp. study,” Bull WorldHealthOrgan, vol. 35, pp. 47–48, 1966. 466–474, 2008. [136] J. B. Gorius, B. Dreyfus, C. Sultan, A. Basch, and J. G. [154] M. J. Woods, M. Greaves, and E. A. Trowbridge, “The d’Oliveira, “Identification of circulating micromegakaryo- physiological significance of circulating megakaryocytes,” cytes in a case of refractory anemia: an electron microscopic- British Journal of Haematology, vol. 80, no. 2, pp. 266–267, cytochemical study,” Blood, vol. 40, no. 4, pp. 453–463, 1972. 1992. [137] K. Yamauchi, J. Miyauchi, and T. Nagao, “Identification of [155] P. E. Stenberg and J. Levin, “Mechanisms of platelet produc- circulating micromegakaryocytes in a case of erythroleuke- tion,” Blood Cells, vol. 15, no. 1, pp. 23–47, 1989. mia,” Cancer, vol. 53, no. 12, pp. 2668–2673, 1984. [156] J. M. Radley and C. J. Haller, “Fate of senescent megakary- [138] M. M. Denis, N. D. Tolley, M. Bunting et al., “Escaping ocytes in thebonemarrow,” British Journal of Haematology, the nuclear confines: signal-dependent pre-mRNA splicing in vol. 53, no. 2, pp. 277–287, 1983. anucleate platelets,” Cell, vol. 122, no. 3, pp. 379–391, 2005. [157] P. G. Fuhrken, C. Chen, W. M. Miller, and E. T. Papout- [139] H. Schwertz, N. D. Tolley, J. M. Foulks et al., “Signal- sakis, “Comparative, genome-scale transcriptional analysis dependent splicing of tissue factor pre-mRNA modulates the of CHRF-288-11 and primary human megakaryocytic cell thrombogenecity of human platelets,” Journal of Experimen- cultures provides novel insights into lineage-specific differ- tal Medicine, vol. 203, no. 11, pp. 2433–2440, 2006. entiation,” Experimental Hematology, vol. 35, no. 3, pp. 476– 489, 2007. [140] H. Schwertz, S. Kost ¨ er, W. H. Kahr et al., “Anucleate platelets generate progeny,” Blood, vol. 115, no. 18, pp. 3801–3809, [158] J.-A. Kim, Y.-J. Jung, J.-Y. Seoh, S.-Y. Woo, J.-S. Seo, and 2010. H.-L. Kim, “Gene expression profile of megakaryocytes from human cord blood CD34+ cells ex vivo expanded by [141] E. M. Dimaano, M. Saito, S. Honda et al., “Lack of efficacy of thrombopoietin,” Stem Cells, vol. 20, no. 5, pp. 402–416, high-dose intravenous immunoglobulin treatment of severe thrombocytopenia in patients with secondary dengue virus infection,” The American Journal of Tropical Medicine & [159] N. Bhamarapravati, S. B.. Halstead, P. Sookavachana, and Hygiene, vol. 77, no. 6, pp. 1135–1138, 2007. V. Boonyapaknavik, “Studies on dengue virus infection. Advances in Virology 15 1. immunofluorescent localization of virus in mouse tissue,” Archives of Pathology, vol. 77, pp. 538–543, 1964. [160] V. M. Reyes, “The pathology of haemorrhagic fever in the Philippines,” Bull World Health Organ, vol. 35, pp. 49–50, [161] N. Bhamarapravati, “The spectrum of pathological changes in Thai haemorrhagic fever,” SEATO Medical Research Mono- graph, vol. 2, pp. 76–80, 1961. [162] P. Piyaratn, “Pathology of Thailand epidemic hemorrhagic fever,” The American Journal of Tropical Medicine & Hygiene, vol. 10, pp. 767–772, 1961. International Journal of Peptides Advances in International Journal of BioMed Stem Cells Virolog y Research International International Genomics Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 Journal of Nucleic Acids International Journal of Zoology Hindawi Publishing Corporation Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 Submit your manuscripts at http://www.hindawi.com The Scientific Journal of Signal Transduction World Journal Hindawi Publishing Corporation Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 International Journal of Advances in Genetics Anatomy Biochemistry Research International Research International Microbiology Research International Bioinformatics Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 Enzyme Journal of International Journal of Molecular Biology Archaea Research Evolutionary Biology International Marine Biology Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Advances in Virology Hindawi Publishing Corporation

Loading next page...
 
/lp/hindawi-publishing-corporation/cells-in-dengue-virus-infection-in-vivo-ZelFP7SQTR

References (167)

Publisher
Hindawi Publishing Corporation
Copyright
Copyright © 2010 Sansanee Noisakran et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ISSN
1687-8639
eISSN
1687-8647
DOI
10.1155/2010/164878
Publisher site
See Article on Publisher Site

Abstract

Hindawi Publishing Corporation Advances in Virology Volume 2010, Article ID 164878, 15 pages doi:10.1155/2010/164878 Review Article 1, 2 1, 3 3 1 Sansanee Noisakran, Nattawat Onlamoon, Pucharee Songprakhon, Hui-Mien Hsiao, 4 1 Kulkanya Chokephaibulkit, and Guey Chuen Perng Department of Pathology and Laboratory Medicine, Dental School Building, Emory Vaccine Center, Emory University School of Medicine, 1462 Clifton Road, Atlanta, GA 30322, USA Medical Biotechnology Unit, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathumthani 12120, Thailand Office for Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand Department of Pediatrics, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand Correspondence should be addressed to Guey Chuen Perng, gperng@emory.edu Received 9 March 2010; Accepted 6 July 2010 Academic Editor: Eric O. Freed Copyright © 2010 Sansanee Noisakran et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Dengue has been recognized as one of the most important vector-borne emerging infectious diseases globally. Though dengue normally causes a self-limiting infection, some patients may develop a life-threatening illness, dengue hemorrhagic fever (DHF)/dengue shock syndrome (DSS). The reason why DHF/DSS occurs in certain individuals is unclear. Studies in the endemic regions suggest that the preexisting antibodies are a risk factor for DHF/DSS. Viremia and thrombocytopenia are the key clinical features of dengue virus infection in patients. The amounts of virus circulating in patients are highly correlated with severe dengue disease, DHF/DSS. Also, the disturbance, mainly a transient depression, of hematological cells is a critical clinical finding in acute dengue patients. However, the cells responsible for the dengue viremia are unresolved in spite of the intensive efforts been made. Dengue virus appears to replicate and proliferate in many adapted cell lines, but these in vitro properties are extremely difficult to be reproduced in primary cells or in vivo. This paper summarizes reports on the permissive cells in vitro and in vivo and suggests a hematological cell lineage for dengue virus infection in vivo, with the hope that a new focus will shed light on further understanding of the complexities of dengue disease. 1. Introduction fever annually, and about 200,000 to 500,000 of these are DHF/DSS, which has a mortality rate about 1%–5%, mainly Dengue is one of the most important mosquito-borne viral in children under 15 years of age [3]. diseases affecting humans, with over half of the world’s Clinically, DF and DHF/DSS have several common population living in areas at risk. Originally, dengue virus features: viremia lasting for 5 to 8 days, fever persisting for infections occurred mainly as epidemics in tropical and 2 to 7 days, headache, myalgia, bone/joint pain, and rash, subtropical countries. But over time, with increasing glob- often accompanied by leucopenia. Occasionally variable alization and the geographic spread of inhabitants of Aedes degrees of thrombocytopenia and cutaneous hemorrhage are aegyti and Aedes albopictus mosquitoes, the dominant vectors observed. More severe cases with incapacitating bone/joint for dengue virus transmission, dengue virus infection has pain (“break-bone-fever”) are common among adults. The steadily penetrated every corner of the world [1, 2]. Dengue pathological hallmarks that determine disease severity and virus has four serotypes, and each of them can cause distinguish DHF from DF and other viral hemorrhagic a spectrum of diseases ranging from asymptomatic, mild fevers are plasma/vascular leakage resulting from increased febrile (dengue fever, DF) to a life-threatening illness, dengue vascular permeability and abnormal hemostasis. Factors and hemorrhagic fever (DHF)/dengue shock syndrome (DSS). biomarkers that can be used to identify those individuals at Approximately 50 to 100 million people contract dengue risk for DHF/DSS are not known. Epidemiological evidence 2 Advances in Virology suggests that preexisting immunity to dengue virus can demonstrable neutralizing antibody to all four dengue enhance disease upon sequential infections [4]. Although serotypes [8], viremia still occurs in some of these popula- intense efforts have been made to identify the etiology of tions upon bitten by mosquitoes carrying infectious dengue DHF/DSS, the potential mechanisms involved in the patho- virus. The reasons why certain individuals developed clinical genesis of DHF/DSS remain an enigma; in large part due to illness are not known, although an individual’s genetic the lack of a satisfactory animal model that recapitulates the background, the interval between reinfection, sequence of clinical sequelae of human dengue virus infection. Currently, infection by specific serotype, and quality of immune there are no effective vaccines or therapeutic drugs available responses may partially account for the differences [4, 8]. to prevent or treat dengue virus infection. The importance of Since identifying the permissive cell lineage(s) in vivo may the dengue, in particular the more severe and potential dire uncover the underlying mechanisms leading to DHF/DSS consequences including death in DHF/DSS, has caught the and aid in vaccine and antiviral drug development, the attention of public concerns, and the NIAID/NIH has listed source(s) of circulating virus in acute dengue patients has dengue virusasaCategory Aprioritybiothreatpathogen been the central focus for several decades. In spite of the [5]. The recent outbreak in Brazil highlights the possibility efforts made to identify these cell(s), the question remains of dengue virus spread to North Americas, thus providing a elusive. potential public health threat to the US as outlined by Dr. Fauci, NIAID [6]. 4. In Vitro Studies Dengue is a timing illness, in other words, the progres- sion to clinical manifestations may differ among infected In vitro, numerous primary cell lineages and established individuals, which has caused variation in time points cell lines have been studied for their relative permissive- of specimen sampling. Currently, many of the descriptive ness for dengue virus infection, including endothelial and events or associated factors related to dengue or dengue fibroblast cells, myeloid-derived cells, and lymphocytes [9– pathogenesis are predominantly derived from the specimens 17]. Although some of the cells defined in vitro could be obtained at the appearance of clinical signs of dengue. permissive cells for dengue virus replication in vivo [18– Because of the lack of early time point in patient samples 21], the actual phenotypes of these cells have not been and suitable or satisfactory animal models, a comprehensive delineated or defined in detail. Consequently, conflicting picture of the events cumulating in DHF/DSS pathogenesis, reports abound in the literature. such as the role of enhancing antibodies, the requirement for Historically, dengue virus has been isolated from poly- specific sequence of infection, the types of cells infected, as morphonuclear leukocytes (PMNs) [22], adherent cells well as the nature and source of the mediators responsible for presumed to be phagocytic monocytes or macrophages [23], increased vascular permeability, is unresolved and constantly and nonadherent leukocytes [24, 25] from dengue patients. in debate. Additionally, since this virus is delivered to its host via In this paper, we summarize or discuss what has been mosquito bites to the skin, the human Langerhans cells, reported thus far on the permissive cells for dengue virus skin cells with a morphology and function similar to that of infection both in vitro and in vivo and propose a new poten- dendritic cells, have been suggested to be a potential target tial permissive cell type that has been neglected frequently for dengue virus infection [26]. Several in vitro studies utiliz- anddeservesmuchmoreattention. ing myeloid-derived dendritic cells have been documented, which suggest the permissive cells upon contact with dengue virus are monocytoid-derived DC-SIGN bearing DCs and 2. Dengue Viruses mannose receptor bearing macrophages [27–33]. In this regard, however, other evidence suggests that Langerhans Dengue viruses, similar to other flaviviruses, possess a pos- and/or dendritic cells are probably implementing their itive single-stranded RNA genome packaged inside a core normal immune functions, such as taking up antigens for protein, which is surrounded by an icosahedral scaffold processing and presenting them to the adaptive immune and encapsidated by a lipid envelope. Its 11 kb genome cells, instead of serving as the reservoir cell for dengue functions similar to mRNA, encoding a polyprotein which virus [21, 34–36]. In addition, it should be noted that upon translation is cleaved into three structural proteins atypical lymphocytes, which may be cells closely related to (C, prM/M, and E) and seven nonstructural proteins (NS1, CD19 B cells, since there is a correlation between these NS2A, NS2B, NS3, NS4A, NS4B, and NS5) by viral or host two cell populations [37], have been regularly reported proteases. Since dengue viral genome can function as mRNA, to be found in increasing frequency, circulating in the if the viral RNA can be delivered into a cell’s cytoplasm peripheral blood of naturally dengue-virus-infected human through biologically active vesicles, translation and genome patients [38, 39]. This uncharacterized cell lineage has been synthesis can occur accordingly [7]. suggested as a potential host cell for the replication of dengue virus in infected patients [22]. As a whole, only a small subpopulation of cells in peripheral blood appears to be 3. Dengue Viremia infected by dengue virus [22, 23], but the phenotype of this Viremia is a common clinical manifestation in several severe subpopulation has yet to be fully characterized. A view on the viral infections. However, dengue viremia is unique because selected suggestive permissive cells is elaborated in a bit more in endemic regions, where majority of the population has detail. Advances in Virology 3 5. Skin Innate Immune Cells of defense mechanism. Thus, if these dendritic cells are permissive as others suggested [27–33], we would anticipate Dengue disease is introduced to its hosts by the bite of quite high incidence of the dengue cases in endemic regions mosquitoes carrying infectious virus. The first obstacle that during the rainy season. The critical role of these antigen the mosquito encounters is the physical barrier of the presenting cells (APCs) is to ingest foreign particles including skin, which is composed of several layers of keratinocytes viruses, process these materials while migrating to the interspersed with a network of capillaries (Figure 1). Ker- regional lymph nodes. Here, the APCs can present the atinocytes are on the outermost epidermal layer of the skin, foreign proteins to other immune cells, such as T cells, are endowed with Toll-like-receptors (TLR) [40], and may to initiate the cascade of the adaptive immune responses, be considered a component of the primary innate immune including antibody production. Dendritic cells, therefore, system. Langerhans cells mainly reside in the thin layer of may be more important for the induction of the host’s the epidermis, which does not contain capillaries, while defense. Importantly, it is of benefit to the host that the virus dendritic cells are predominantly in the thicker dermis layer, be engulfed and processed in order to generate an adequate which is filled with capillaries. Although Langerhans cells, immune response against the invading pathogen and protect in general, have the same phenotype as dendritic cells, the host from further infection. Since such phagocytic cells and is impossible to distinguish activated Langerhans cells are the first line of defense in our body, this may perhaps from dendritic cells by morphological appearance, numerous explain why a majority of dengue cases are asymptomatic. studies indicate that biological activities are discernible Interestingly, apoptotic keratinocytes and dendritic cells between these two cell types [41–44]. Many interesting are observed in human skin explants when dengue virus questions can be asked. How does dengue virus interact with is directly injected into the epidermis with a fine needle skin cells during mosquito probing prior to penetration? [35]. Furthermore, others have observed that mosquitoes How deep does the mosquito fascicle penetrate into the skin? can deposit high doses of virus extravascularly as they probe How does dengue virus behave upon contacting epidermal and feed on the host, while only a small amount of virus and dermal innate immune cells after the mosquito fascicle is injected directly into the blood [50]. Considering the fact penetrates? And how does dengue virus get deposited and that a majority of dengue virus infections are asymptomatic, disseminated during the engorgement period while the this evidence suggests that the role of dendritic cells at the site mosquito imbibes the blood? The answers to these questions of fascicle penetration is to eliminate or temporarily contain can elucidate how the fates of the cells on or in the skin are the intruders and thereby prevent or reduce the dissemina- orchestrated. tion of dengue virus. However, the role of keratinocytes and dendritic cells in clearance of dengue virus remains to be further investigated. 6. Mosquito Imbibing Gordon and Lumsden, the authors of a historical in vivo 8. Monocytes/Macrophages frog’s web paper in 1939, observed that the mosquito’s proboscis is flexible and predominantly imbibes blood Since dengue viral antigens are detectable in adherent cells directly from the capillary and only occasionally from obtained from the peripheral blood of dengue patients, the pools formed in the tissues by the leakage of blood monocytes and/or macrophages have been an assumptive from the capillary previously lacerated by the mosquito’s target cell for more than three decades. With the high level proboscis [45]. This study is later confirmed in mice ear and of interest in the pathogenesis of DHF/DSS, intensive efforts human beings implementing the same experimental designs have been made to identify the infected monocytes and/or [46, 47]. The dimensions of an Aedes aegypti fascicle are macrophages in the peripheral blood of infected patients, typically 1.8 mm in length with an internal radius of 10 μm andsomesuggestivesuccesseshavebeendocumented. [48] and typically engorge a blood meal of 4.2 μl in 141s However, dengue is a timing disease. Specimens collected [48]. It is estimated that during imbibing, approximately from dengue patients are often after the onset of clinical 50% (∼0.9 mm) of the fascicle penetrates into skin [49], manifestations; therefore, the intervals prior to symptoms suggesting that the location of blood drawn from is the developed are different among individuals and are likely capillary-rich dermis layer, implicating that pathogens may at the peak of dengue viremia, and autopsy samplings are be directly injected into the blood. always at the convalescent stage or later. Within the context, identifying a cell that is positive for dengue viral antigens in collected specimens requires meticulous investigations and 7. Dendritic and Langerhans Cells cautious interpretations. Although recently researchers are Mosquito probing, penetration, and feeding on the surface attempting to address the issue with small animal models, of the skin is easily interrupted by the movement of the such as the AG129 mice experimentally infected with dengue host. Unsuccessful imbibing may result in a certain amount virus, the major pitfall of this model is that mice have of virus deposited on the outermost layers of skin, where a defective interferon response, which has been shown to keratinocytes, Langerhans, and dendritic cells may encounter play averycriticalroleincontrolling virusreplication and the virus. The delicate alarm system of the skin can sense the proliferation. Consequently, dengue viral RNA or antigens probing of the mosquito and the penetration of the fascicle, are observed in almost all the cells and organs that have been potentially initiating a signaling cascade and the activation investigated [18, 21]. Within the same content, this same 4 Advances in Virology DC LC Keratinocytes Stratum corneum (0.01 − 0.02 mm) Epidermis (0.03 − 0.13 mm) Basal cells Dermis (1.1mm) Capillary Subcutaneous fat (1.2 mm) Muscle base Figure 1: A schematic diagram of the skin. A cartoon drawing based upon the textbook descriptions of the thickness of outer skin layers. Only layers relevant to the subject are shown. LC, Langerhans cells; DC, dendritic cells; Capillary, green and red internetworks. group investigated the autopsy tissues from patients who infection. However, if stainings included a specific marker died of dengue virus infection. The authors showed that for platelets and/or megakaryocytes, it may help distinguish human tissues and the corresponding mice AG129 tissues the phenotype of the dengue virus infected cells. Although were positive for dengue virus NS3 antigen, concluding these studies demonstrated that dengue viral antigens or that these cells propagated virus. However, the phenotypic RNA were observed in certain cell populations, the definitive markers of the cells that were positive for dengue viral phenotype was not determined. Therefore, in vivo, the antigen were not confirmed, and thus a conclusion was cell(s) accounting for viremia during dengue virus infection drawn based upon the similarities between humans and remains an enigma. mice. Also, a new finding suggests that liver sinusoidal CD31+ endothelial cells in AG129 mice are positive for 9. Historical Observations dengue viral antigen and can support the antibody-mediated infection [21]. However, evidence indicates that there are Retrospective literature reviews reveal that in bone mar- many differences in immunological and antiviral responses rows aspirated during the recovery stage or immediately between humans and mice [51–53]. Thus, clarifications of after death, phagocytic clasmatocytes contain normoblastic, the role of monocytes and macrophages in dengue virus lymphocytic, granulocytic, erythrocytic, and platelet-like infection in vivo are urgently needed. This notion is also remnants in their cytoplasm [60–62]. Infected leukocytes (or applied to the paper published by Jessie et al. [20], in which monocytes) are frequently present on the last day, at the end the cell phenotype markers in those cells positive staining for of viremia, or the day after the disappearance of the virus either dengue viral antigens or RNA, were not confirmed. from the plasma [63], suggesting that leukocytes may play an In addition, Durbin et al. [19] has performed an exten- essential phagocytic role in the clearance of circulating virus. sive phenotyping of PBMCs during acute dengue illness, Recently, the phagocytic phenomenon has been confirmed in and the results suggest that quite a few immune cells with dengue hemorrhagic nonhuman primate model [64]. Due to variouscellsurface markersare positive forviral antigens, difficulties and inconsistencies in identifying the cell lineages prM or NS3. Recently, in a study with AG129 mice, dengue responsible for dengue viremia at the acute stage, monocytes antigens are seen in CD31 liver cells stained with the same and/or macrophages are gradually being assumed as the antibody [21]. However, these observations can be explained main cells for dengue virus propagation for the following by several factors. One of such alternative explanation is reasons: (i) like the cells that can propagate the virus, they platelet-leukocyte aggregation, which has been documented canadheretocellculture flasks[63, 65], (ii) they are capable to occur in a number of physiological and pathological of phagocytosis [23, 66], and (iii) infrequently observed states [54–58] and has been implicated in contributing dengue viral antigens in cells with a similar morphology in to inflammation [54, 57, 59]. Another possibility is that tissues obtained postmortem [20, 67, 68]. These observations multiple cell types can be stained with the same cell markers; then led to the postulated hypothesis of antibody-dependent for example, megakaryocytes and platelets can be stained enhancement (ADE) [69] in an attempt to explain the with CD31-specific antibody. Whether the virus actively epidemiological observation in which secondary infection replicates in these cells was not shown, and thus the dengue with subsequent heterologous dengue serotypes is a risk viral antigen detected in these cells may be the result of factor for DHF/DSS [70]. The ADE theory is used to engulfed materials or undigested protein residue via in vivo explain the severe dengue virus infection; antibody to the deposition of virus-antibody complexes rather than direct first infection may not be sufficient enough to neutralize Advances in Virology 5 a heterologous infection, and this partial cross-reacting anti- cancer cells, such as lymphoma and leukemia and established body (or subneutralizing antibody) may promote Fc-bearing immortalized cell lines [84–88]. This line of evidence may, to cells such as monocytes and macrophages to opsonize the some extent, explain why cell lines, such as Vero and K562 virus, leading to increased virus production. cells, which lack a functional interferon system, are highly permissive to dengue virus infection. In addition, activation However, studies have shown that some hematopoietic of interferon-stimulated genes are the constant findings in cells have the adherence and phagocytic property as well cells with relatively poor permissive for dengue virus [14, [71], and consequently reports on the ADE hypothesis 89, 90] and in specimens obtained in dengue-virus-infected are in debate. In support of this view, in the presence of humans and rhesus monkeys [89, 91, 92]. Within the same subneutralizing antibody, a low percentage of dengue virus content, it is interesting to review what has been investigated infected monocytes and/or macrophages can be observed in paucity of dengue animal models. in vitro [72–74]. On the contrary, some reports indicate that monocytes and/or macrophages have a different role— to protect against dengue virus replication. Evidences in 11. In Vivo Animal Studies support of this view include: (i) monocytes/macrophages Currently, no perfect animal model that recapitulates the undergo apoptosis in contact with dengue virus, (ii) they cardinal features of human DHF/DSS is available, even are capable of phagocytosis, (iii) they phagocytose infected though a recent dengue hemorrhagic monkey model appears apoptotic cells or apoptotic bodies, and (iv) they upregulate to be promising for dengue hemorrhagic investigation [64]. immune responses through autocrine or paracrine cytokine Since understanding the mechanisms leading to viremia mechanisms [15, 64, 75–80]. and disease is necessary for vaccine and antiviral drug An interesting discrepancy abounds. If monocytes and/or development, efforts have been made to search and/or macrophages are the cells accounting for viremia during generate a suitable dengue animal model. The readers should acute infection, why is it so difficult to detect the viral refer to recent review articles on the subject in smaller antigens in peripheral blood cells obtained from acute animals [93, 94]. This paper focuses mainly on why dengue dengue patients? The aforementioned scenario—protective viremia is seen in these animal models. against dengue virus may account for the answer. With the The absence of disease symptoms, virus replication, and evidence available in vivo to date, it is more reasonable to viremia in the serum of laboratory immunocompetent mice assume that the presence of dengue viral antigens within strains [95–98] indicates these mice are not suitable to study monocytes in samples obtained towards the end of the the cells permissive for dengue virus infection. In contrast, acute infection period may be the result of phagocytosis and in immunocompromised mice, such as AG129, A/J, and viral clearance. Interestingly, a recent report also suggests −/− STAT mice [99–102], dengue viremia can be observed, a prominent role of monocytes and/or macrophages in the though to some levels, in serum and in almost all the major control of dengue virus in infected mice [81]. Unfortunately, organs studied. Thus, in immunocompromised mice, the the role of monocytes and/or macrophages in dengue virus interferon system may have defects that enhance disease infection has drawn the center attention for more than unnaturally. Taking this into account, it is improbable that three decades, yet the importance they play in the patho- identification of the potential permissive cells for dengue genesis of DHF/DSS is still unclear. Recently, an immuno- virus replication will result from investigations with this competent nonhuman primate model recapitulating the model. In studies involving human chimeric mice, dengue dengue hemorrhagic is available [64], the mystified issue virus appears to be detected predominantly in the human on the role of monocytes and/or macrophages in dengue implanted or immortalized cells [103–109], suggesting that virus infection may be further delineated and hopefully only the cells of human origin are infected and mice tissue resolved. can not support viremia. Nevertheless, as a whole, despite having a few drawbacks, such as low to undetectable dengue 10. Biological Characteristics in antibody in serum, and to some extent, lack of typical characteristics of dengue disease [108], currently a small Cells Infected by Dengue Virus animal model with detectable viremia, perhaps would be The reason why dengue viruses are capable of infecting ideal for the initial screening of antiviral compounds and/or a wide range of immortalized cell lines, such as myeloid- vaccine toxicity studies. However, the rhesus macaque animal originated, B, T, fibroblast, and endothelial cells but yet model is more appropriate for investigations involving the comparatively poor at replicating in primary cells is currently cells responsible for dengue viremia. unknown. Perhaps, it is likely that cell factors that are altered The only large animal species besides humans that are in immortalized cell lines contribute to this differential known to be naturally infected and can be experimentally permissiveness. Immortalized cell lines are normally trans- infected by the parenteral route are monkeys [110–115] formed with viruses, such as SV40 or EBV, which encode viral and apes [97]. The antibody response and viremia levels gene products that have an effect on interferon-signaling. in monkeys are similar to that seen in humans [111], and Interestingly, among the cell mediator repertoire, interferon therefore they have been viewed as an acceptable animal expression appears to be a very crucial element limiting model to study virological and immunological aspects in the propagation of dengue virus [14, 82, 83]. In addition, experimental dengue virus infections [116–119]. In addition, defects in interferon signaling pathway has been shown in it has been well documented that in all aspects, the cell 6 Advances in Virology composition of rhesus macaque bone marrow is very similar patients remain unknown. Also, the interactions of dengue to that of humans [120, 121] and is highlighted by the virus with platelets, including entry and possible virus fact that the parameters established for blood transfusions production, have not been investigated. in monkeys has served as an important guide for these We have proposed that platelets may be a critical procedures in clinical studies [122]. Furthermore, a recent element in early dengue virus infection [131–133], which report demonstrated a recapitulation of human dengue hem- may partially account for the dysfunction of platelets. orrhagic in rhesus monkeys via intravenous administration Subsequent systematic investigations, with biological assays of high doses of dengue virus [64]. Even though the level and and electron microscopy, reveal that dengue viral RNA, magnitude of dengue viremia is slightly lower than that of either the positive stranded genome or negative stranded humans, this model displayed disease symptoms and thus is template, and the presence of mature virus-like particles, a better animal to investigate the source of dengue viremia. are consistently observed in platelets isolated from dengue However, a systematic investigation to identify the potential confirmed patients during the acute phase of infection cells for dengue viremia in this model has not been explored [132, 133]. A micrograph of dengue virus-like particles in depth due to limited accessibility of the resources and the within platelets isolated from confirmed dengue patients is high cost of the model. Thus, this topic will be evaluated with depicted (Figure 2). Typical clustering of dengue virus-like samples collected from dengue-infected patients. particles surrounded by a vesicle was observed in platelets (Figure 2(a)), and occasionally single or isolated dengue virus-like particles were observed [133]. Infrequently, dengue 12. In Vivo Dengue Patients virus-like particle with a fuzzy morphology were observed associated with or released from platelets (Figure 2(b)). Studies over the years with specimens collected from the However, we could not rule out the possibility that these peripheral blood of dengue patients reveal that virus can be dengue virus-like particles containing platelets are in the recovered or detected in a variety of cells. However, a general category of megakaryocyte-derived microparticles [134]. In consensus concerning which cell lineages are involved in addition, immunofluorescent staining of platelets isolated dengue viremia has never been conclusive, partly due to the from confirmed dengue patients reveals that viral antigens variation of timing in specimen collection. Upon admission can be observed not only in platelets, but also in cells with to the hospital with clinical symptoms, patients are always the similar morphology as proplatelets (Figure 3(a)), while several days after the infection and frequently at the peak some dengue viral antigens were observed in presumably or downturn in viremia. By that time, a complex network the micromegakaryocytes (Figure 3(b)). This observation of immune responses initiated and is in the action of viral is consistent with early reports by Nelson et al. [61, 126], clearance. Perhaps, this may explain why immune cells are who originally observed the presence of immature and commonly associated with the detection and/or isolation of nonplatelet forming megakaryocytes circulating in dengue virus in dengue patients [24]. Thus, the cells that are infected patients and by Bhamarapravati and Boonyapaknavik [135], early, before the peak in viremia, and accounting for dengue who noted that positive staining for dengue viral antigen viremia are still unknown. in human tissues was demonstrated only in the lymphoid- like cells. Interestingly, the nucleated micromegakaryocytes, 12.1. Platelets in Dengue. One of the important clinical which are similar in size and morphology to lymphocytes, hallmarks in dengue virus infection in patients is platelet have been well documented [136, 137]. The presence of micromegakaryocytes, as opposed to megakaryocytes, dysfunction, which occurs throughout the acute phase, and/or thrombocytopenia, which frequently occurs at the suggests that production of platelets from bone marrow defebrile stage, thus this is a subject of interest, especially increases in response to dysfunctional or low numbers of in understanding the possible mechanisms leading to the platelets in the circulation of acute dengue patients. observed phenomena. There are a few proposed mechanisms Although platelets do not have a nucleus, they possess functional spliceosomes that are able to process pre-mRNAs that may explain platelet dysfunction and/or thrombocy- topenia: (i) decreased production, (ii) direct infection by into mature mRNA, from which proteins can be translated virus, (iii) increased consumption, or (iv) immune-complex and processed [138, 139]. In vitro experiments were set up to lysis. The first mechanism has been observed. Early in investigate the susceptibility of platelets to support dengue infection of dengue virus, it exerts a transient depressive virus production, which may directly contribute to the effect on megakaryocytes in the bone marrow [123–126], platelet dysfunction. A low level of dengue virus production which subsequently becomes normocellular or hypercellular could occur in infected platelets with the peak occurring at 18 a few days after onset of fever [61, 124, 126]. In vitro hours post infection (Figure 4), suggesting that dengue virus and in vivo, dengue virus has been demonstrated to have is capable of replicating in platelets and dengue viral antigens toxic effects on platelets in the presence and absence of may be expressed on the surface of platelets. Alternatively, acute and convalescent patient serum, lending some support the moderate viremia changes may result from the transient ability of platelets reproduction in culture conditions [140], for the second mechanism [127–129]. In addition, dengue viral RNA has been isolated from or detected in platelets which may have the capacity of capturing and releasing isolated from secondary dengue virus infected patients [130]. dengue viruses in later hours. Perhaps, this may account However, the precise mechanisms for the development of for the rise of platelet-associated antibodies (PAIgM/IgG) dysfunctional platelets and thrombocytopenia in dengue during acute dengue virus infection [130] and the increased Advances in Virology 7 100 nm 143 nm 250 nm (a) (b) Figure 2: Dengue virus-like particles in platelets isolated from confirmed dengue patients. Platelets were isolated from confirmed dengue patients at the acute stage and subjected to electron microscopy. (a) Dengue virus-like particles were observed inside vesicle compartment (red arrow) and a particle appeared to be on its way budding out into the vesicle (blue arrow). (b) A single fuzzy virus-like particle was released from platelet (red arrow head). Red circle indicates the enlarged area. Insert is the platelets. incidence of phagocytosis of platelets from patients with platelets are demarcated from the membrane of megakary- secondary infections by human macrophages [78]. In addi- ocytes, which may result in heterogeneous populations of tion, administration of intravenous immunoglobulin, which platelets. This heterogeneity of platelet alloantigen referred saturates phagocytosis and impedes antibody production, to as human platelet alloantigen (HPA) polymorphism in the lacked efficacy when used to treat severe thrombocytopenic literature, and how it contributes to dengue virus infection patients with secondary dengue virus infection [141]. As a and dengue disease severity warrants further investigation. whole, these evidences suggest that dengue virus may take a ride and experience ongoing maturation within platelets 12.2. Megakaryocyte-Erythroid Progenitor (MEP) Cells in produced from infected progenitor megakaryocytes. Dengue. Hematopoietic progenitor cells (HPCs) normally Platelets are anucleate cells that have hemostatic and reside in bone marrow but can be mobilized to peripheral inflammatory functions [142, 143] and are composed of blood by stimulation with cytokines/chemokines. During a concentrate of megakaryocyte membrane, cytoplasm, infection, the microenvironment within the circulation granules, and organelles [144]. Platelets circulate throughout contains a variety of immune cytokines/chemokines. Some blood vessels during which they monitor the integrity of of these immune cytokines/chemokines have the capacity the vascular system. All functional platelet responses must to mobilize HPC to peripheral blood in response to the + + be tightly regulated to ensure that the formation of blood CD61 cells, such as megakary- invading pathogen. CD41 clots is of sufficient size to seal off the damaged area, while ocytes, normally account for 1% of the bone marrow but not disrupting blood flow to vital organs by causing vessel can change dramatically in certain diseases or infections occlusion [145–147]. With the observation that dengue and mobilize into the peripheral circulation. However, the viral antigens are associated with proplatelets [148, 149] presence of megakaryocytes in blood is a normal phys- or micromegakaryocytes [137, 150] in blood during acute iological occurrence [154]. Transport of megakaryocytes dengue virus infection (Figure 3), it is likely that a platelet in the blood is halted in the lungs, where the majority lineage parental cell, megakaryocytes, may be involved in shed their cytoplasm. Upon maturation via differentiation, the production of dengue virus during acute infection. In the process of releasing platelets is initiated. Cytokines, addition, platelets contain several key elements related to such as thrombopoietin, can orchestrate the formation of dengue virus infection, such as DC-SIGN [151]aswellas platelets, which are held within the internal membranes in complement and Fc receptor, which have been implicated the cytoplasm of megakaryocytes. Platelets are released via in virus uptake [152, 153]. It is also possible that a unique two proposed scenarios [155]; (a) megakaryocytes undergo receptor or coreceptor is required for viral binding and entry apoptosis to break up the platelets from demarcation of into platelets. However, this particular receptor or coreceptor membranes, and (b) formation of platelet pseudopodia may not be evenly distributed or allocated in platelets since ribbons (proplatelets), which are released into blood vessels 8 Advances in Virology 10 nm 10 nm 10 nm 10 nm 10 nm (a) 10 nm 10 nm 10 nm 10 nm 10 nm (b) Figure 3: Dengue antigens on platelets and its derivative cells. Isolated platelets were stained with dengue-specific antibody (3H5) and platelets-specific markers (CD41). (a) Dengue antigen was observed in platelets and proplatelets. (b) Dengue antigen was observed in a micromegakaryocyte. Green: platelet marker CD41; Red: dengue antigen; and Blue; DAPI for nucleus staining. Red bar, 10 μm. resulting in continuously release of platelets into the circula- Recently, a study profiling the gene expression by tion. In either scenario, each megakaryocyte can give rise to genome-scale transcriptional analysis in human primary 1000–3000 platelets [155], of which 2/3 of newly produced megakaryocytic cell reveals that interferon-response genes platelets remain in circulation while 1/3 is sequestered within are not induced or responsive to culture conditions or PMA the spleen. The remaining cell nucleus of the megakaryocyte, treatment [157, 158], suggesting that there is a possible which is covered with a very thin cytoplasmic membrane signaling defect in or impairment of interferon signaling in and is morphologically similar to the small lymphocytes megakaryocytes. Thus, bone marrow suppression observed [137, 156], then crosses the bone marrow barrier into the in dengue patients during the acute stage of infection, blood and is consumed in the lung by macrophage-mediated including reduction of megakaryocytes [61, 123, 125], may phagocytosis [156]. be due to direct disturbance or infection by dengue virus. Advances in Virology 9 10 While dengue virus or its antigens has been found in sev- eral tissues and cells [15, 18, 20, 67, 162]frompostmortem autopsy specimens and much important information has been generated; one thing has to be kept mind. By the time most of the patients are ill enough to be hospitalized, 10 they are at the end stage of the dengue virus infection, multiple organ lesions or failures have occurred, and the virus or viral antigens may be trapped in these tissues and/or engulfed by phagocytic cells. Furthermore, a large number of macrophages containing what appears to be incompletely 10 digested nuclear debris can be observed in autopsy specimens [62, 67, 161, 162], while the endothelial cells of the blood vessels look normal [67, 161, 162]. In addition, since dengue virus causes viremia in infected patients and the timing of the autopsy specimen collections are very critical, interpretation 10 of outcomes may be complicated by the constant blood 2 6 18 24 48 circulation in the body system when the patients are in Hours P.I. consciousness. As a whole, at present, it is impossible to decipher the actual meaning of viral antigens or RNA in Pellet cells observed in autopsy specimens. With the recent suitable Supernatant animal model, which is capable of recapitulating human Figure 4: Transient replication of dengue virus in platelets. Platelets dengue hemorrhages [64], the status of these cells may be were isolated from a healthy donor and experimentally infected with clarified in the near future. dengue virus serotype 2 (strain 16681) at an MOI of 0.01. RNA In summary, although many cell types including those was isolated from supernatants and pellets at indicated time and paired with ADE capacity may play a role in dengue subjected to real-time qRT-PCR for dengue viral RNA. virus infection and in the development of DHF/DSS, this paper by no means suggests that cells with an impaired interferon system are the cells accounting for dengue viremia Interestingly, damaged or degenerated megakaryocytes with homogenous hyalinized or reduced cytoplasms in bone in vivo. Instead, this current paper addresses the observed marrow biopsies from acute patients have been documented phenomena in the literature and summarizes the possible [61, 123, 135, 159, 160]. Additionally, autopsies performed scenarios. In addition, a new cell is suggested to have a role in in patients who died of acute dengue hemorrhagic fever DHF/DSS pathogenesis and warrants further investigation. in the early 1960s revealed an increase in the number of megakaryocytes in the capillaries of various organs [161]and 13. Conclusions the deposition of hyaline materials with large mononuclear cells of varying maturity in the germinal centers of the spleen + + A new lineage of cell—MEP or CD41 CD61 cells, such as [162]. megakaryocytes and/or platelets—is suggested for a potential Furthermore, a unique and previously neglected cell cell accounting for dengue viremia in vivo. The objective population, which has ultrastructural and morphological of the authors is to draw scientific attention to the highly appearance similar to that of micromegakaryocytes [137, fragile cell with unusual biological properties in acute 150]and apossiblesourceofdengue viremia[22, 123], dengue virus infection. After all, hemostatic defects in DHF were seen in circulation during the acute phase of infection appear to be a major clinical finding. Our aim is to foster [129, 160], though the likely phenotypes of these neglected + + more detailed investigations of the MEP or CD41 CD61 cells are not well defined. cells in specimens collected from acute dengue patients, In addition, bone marrow aspiration studies show that which conceivably will not only provide a piece of valuable erythroid cells are diminished transiently in all cases of information of the mechanisms associated with DHF/DSS, dengue, some with an arrest of maturation [124, 126]. but will also pave a new way on the formulation of effective However, due to the long half-life of red blood cells candidate vaccines or antiviral drugs development. in circulation, the transiently halted erythropoiesis does not cause severe anemia in dengue patients. This line of evidence suggests a possibility of a transient involvement of Acknowledgments megakaryocyte-erythroid progenitor (MEP) cells in dengue virus infection. Whether direct infection of MEP cells or The authors thank the clinical staffs in the Department of megakaryocytes by dengue virus can induce an aberrational Pediatrics, Siriraj Hospital for technical assistance in patient transcriptional event, such as a disturbance of nucleic acid blood collection. The authors appreciate Kristina Bargeron synthesis, resulting in the transiently halted erythropoiesis or Clark and David Clark for their kindness of editing the increased production of immature megakaryocytes and atyp- paper as well as the kind and knowledgeable assistance of ical lymphocytes circulating in the blood remains unclear Dr. Hong Yi from Electron Microscopy Core Facility of the and warrants more exploration. Emory University School of Medicine. The paper is partially Viral RNA (copies/mL) 10 Advances in Virology supported by U19 Pilot Project Funds (RFA-AI-02-042), human lymphoblastoid cells and subpopulations of human peripheral leukocytes,” Journal of Immunology, vol. 117, no. NIH/SERCEB, and Emory URC grants. 3, pp. 953–961, 1976. [18] S. J. Balsitis, J. Coloma, G. Castro et al., “Tropism of dengue virus in mice and humans defined by viral nonstructural References protein 3-specific immunostaining,” The American Journal [1] G.Clark,D.Gubler, andJ.DengueFever, CDC Traveler’s of Tropical Medicine & Hygiene, vol. 80, no. 3, pp. 416–424, Information on Dengue Fever, Centers for Disease Control, 2009. Atlanta, Ga, USA. [19] A. P. Durbin, M. J. Vargas, K. Wanionek et al., “Phenotyping [2] M.G.Guzman, ´ G. Kour´ı, M. D´ıaz et al., “Dengue, one of the of peripheral blood mononuclear cells during acute dengue great emerging health challenges of the 21st century,” Expert illness demonstrates infection and increased activation of Review of Vaccines, vol. 3, no. 5, pp. 511–520, 2004. monocytes in severe cases compared to classic dengue fever,” [3] WHO, Prevention and Control of Dengue and Dengue Haem- Virology, vol. 376, no. 2, pp. 429–435, 2008. orrhagic Fever, WHO, SEARO, 1999. [20] K. Jessie, M. Y. Fong, S. Devi, S. K. Lam, and K. T. Wong, [4] S. B. Halstead, “Dengue,” The Lancet, vol. 370, no. 9599, pp. “Localization of dengue virus in naturally infected human 1644–1652, 2007. tissues, by immunohistochemistry and in situ hybridization,” [5] NIAID, Dengue Fever, 2005. Journal of Infectious Diseases, vol. 189, no. 8, pp. 1411–1418, [6] D. M. Morens and A. S. Fauci, “Dengue and hemorrhagic fever: a potential threat to public health in the United States,” [21] R. M. Zellweger, T. R. Prestwood, and S. Shresta, “Enhanced Journal of the American Medical Association, vol. 299, no. 2, infection of liver sinusoidal endothelial cells in a mouse pp. 214–216, 2008. model of antibody-induced severe dengue disease,” Cell Host [7] T.J.Chambers, C. S. Hahn, R. Galler, andC.M.Rice, “Fla- and Microbe, vol. 7, no. 2, pp. 128–139, 2010. vivirus genome organization, expression, and replication,” [22] R. M. Scott, A. Nisalak, and U. Cheamudon, “Isolation of Annual Review of Microbiology, vol. 44, pp. 649–688, 1990. dengue viruses from peripheral blood leukocytes of patients [8] N. Sangkawibha, S. Rojanasuphot, and S. Ahandrik, “Risk with hemorrhagic fever,” Journal of Infectious Diseases, vol. factors in dengue shock syndrome: a prospective epidemi- 141, no. 1, pp. 1–6, 1980. ologic study in Rayong, Thailand. I. The 1980 outbreak,” [23] S. B. Halstead, E. J. O’Rourke, and A. C. Allison, “Dengue American Journal of Epidemiology, vol. 120, no. 5, pp. 653– viruses and mononuclear phagocytes. II. Identity of blood 669, 1984. and tissue leukocytes supporting in vitro infection,” Journal [9] B. S. Andrews, A. N. Theofilopoulos, and C. J. Peters, of Experimental Medicine, vol. 146, no. 1, pp. 218–229, 1977. “Replication of dengue and junin viruses in cultured rabbit [24] A. D. King, A. Nisalak, S. Kalayanrooj et al., “B cells are the and human endothelial cells,” Infection and Immunity, vol. principal circulating mononuclear cells infected by dengue 20, no. 3, pp. 776–781, 1978. virus,” Southeast Asian Journal of Tropical Medicine and Public [10] M. T. Arevalo ´ , P. J. Simpson-Haidaris, Z. Kou, J. J. Health, vol. 30, no. 4, pp. 718–728, 1999. Schlesinger, and X. Jin, “Primary human endothelial cells [25] R. Scott, A. Nisalak, and U. Cheam-u-Dom, “A preliminary support direct but not antibody-dependent enhancement of report on the isolation of viruses from the platelets and dengue viral infection,” Journal of Medical Virology, vol. 81, leukocytes of dengue patients,” Asian Journal of Infectious no. 3, pp. 519–528, 2009. Diseases, vol. 2, no. 1, pp. 95–97, 1978. [11] A. Azizan, K. Fitzpatrick, A. Signorovitz et al., “Profile of [26] S.-J. L. Wu, G. Grouard-Vogel, W. Sun et al., “Human time-dependent VEGF upregulation in human pulmonary skin Langerhans cells are targets of dengue virus infection,” endothelial cells, HPMEC-ST1.6R infected with DENV-1, - Nature Medicine, vol. 6, no. 7, pp. 816–820, 2000. 2, -3, and -4 viruses,” Virology Journal, vol. 6, article 49, 2009. [27] J. L. Kyle, P. R. Beatty, and E. Harris, “Dengue virus infects [12] C. Cabello-Gutier ´ rez, M. E. Manjarrez-Zavala, A. Huerta- macrophages and dendritic cells in a mouse model of Zepeda et al., “Modification of the cytoprotective protein C infection,” Journal of Infectious Diseases, vol. 195, no. 12, pp. pathway during Dengue virus infection of human endothelial 1808–1817, 2007. vascular cells,” Thrombosis and Haemostasis, vol. 101, no. 5, [28] M. Marovich, G. Grouard-Vogel, M. Louder, et al., “Human pp. 916–928, 2009. dendritic cells as targets of dengue virus infection,” Journal of [13] I. Kurane, D. Hebblewaite, W. E. Brandt, and F. A. Ennis, Investigative Dermatology Symposium Proceedings, vol. 6, no. “Lysis of dengue virus-infected cells by natural cell-mediated 3, pp. 219–224, 2001. cytotoxicity and antibody-dependent cell-mediated cytotox- [29] J. L. Miller,B.J.M.DeWet,L.Martinez-Pomaresetal., icity,” Journal of Virology, vol. 52, no. 1, pp. 223–230, 1984. “The mannose receptor mediates dengue virus infection of [14] I. Kurane and F. A. Ennis, “Production of interferon alpha by macrophages,” PLoS Pathogens, vol. 4, article e17, 2008. dengue virus-infected human monocytes,” Journal of General [30] Z. D. Nightingale, C. Patkar, and A. L. Rothman, “Viral Virology, vol. 69, part 2, pp. 445–449, 1988. replication and paracrine effects result in distinct, functional [15] I. Kurane, U. Kontny, J. Janus, and F. A. Ennis, “Dengue- responses of dendritic cells following infection with dengue 2 virus infection of human mononuclear cell lines and 2 virus,” Journal of Leukocyte Biology, vol. 84, no. 4, pp. 1028– establishment of persistent infections,” Archives of Virology, 1038, 2008. vol. 110, no. 1-2, pp. 91–101, 1990. [31] P. Sun, S. Fernandez, M. A. Marovich et al., “Functional [16] S. Sriurairatna, N. Bhamarapravati, A. R. Diwan, and S. B. characterization of ex vivo blood myeloid and plasmacytoid Halstead, “Ultrastructural studies on dengue virus infection dendritic cells after infection with dengue virus,” Virology, of human lymphoblasts,” Infection and Immunity, vol. 20, no. vol. 383, no. 2, pp. 207–215, 2009. 1, pp. 173–179, 1978. [32] B. Tassaneetrithep, T. H. Burgess, A. Granelli-Piperno et al., [17] A. N. Theofilopoulos,W.E.Brandt,P.K.Russell,and F. T. Dixon, “Replication of dengue 2 virus in cultured “DC-SIGN (CD209) mediates dengue virus infection of Advances in Virology 11 human dendritic cells,” Journal of Experimental Medicine, vol. [46] R. B. Griffiths and R. M. Gordon, “An apparatus which 197, no. 7, pp. 823–829, 2003. enables the process of feeding by mosquitoes to be observed in the tissues of a live rodent; together with an account of [33] J. P. Wang,P.Liu,E.Latz, D. T. Golenbock, R. W. Finberg, the ejection of saliva and its significance in Malaria,” Annals and D. H. Libraty, “Flavivirus activation of plasmacytoid of Tropical Medicine and Parasitology, vol. 46, no. 4, pp. 311– dendritic cells delineates key elements of TLR7 signaling 319, 1952. beyond endosomal recognition,” Journal of Immunology, vol. 177, no. 10, pp. 7114–7121, 2006. [47] F. J. O’Rourke, “Observations on pool and capillary feeding in aedes aegypt,” Nature, vol. 177, no. 4519, pp. 1087–1088, [34] W.-H. Kwan, E. Navarro-Sanchez, H. Dumortier et al., “Dermal-type macrophages expressing CD209/DC-SIGN show inherent resistance to dengue virus growth,” PLoS [48] T. L. Daniel and J. G. Kingsolver, “Feeding strategy and the Neglected Tropical Diseases, vol. 2, no. 10, article e311, 2008. mechanics of blood sucking in insects,” Journal of Theoretical [35] A. Y. Limon-Flores, M. Perez-Tapia, I. Estrada-Garcia et Biology, vol. 105, no. 4, pp. 661–677, 1983. al., “Dengue virus inoculation to human skin explants: an [49] M. K. Ramasubramanian, O. M. Barham, and V. Swami- effective approach to assess in situ the early infection and the nathan, “Mechanics of a mosquito bite with applications to effects on cutaneous dendritic cells,” International Journal of microneedle design,” Bioinspiration and Biomimetics, vol. 3, Experimental Pathology, vol. 86, no. 5, pp. 323–334, 2005. no. 4, Article ID 046001, 2008. [36] S. Taweechaisupapong, S. Sriurairatana, S. Angsubhakorn, S. [50] L. M. Styer, K. A. Kent, R. G. Albright, C. J. Bennett, L. Yoksan, and N. Bhamarapravati, “In vivo and in vitro studies D. Kramer, and K. A. Bernard, “Mosquitoes inoculate high on the morphological change in the monkey epidermal doses of West Nile virus as they probe and feed on live hosts,” Langerhans cells following exposure to dengue 2 (16681) PLoS Pathogens, vol. 3, no. 9, pp. 1262–1270, 2007. virus,” Southeast Asian Journal of Tropical Medicine and Public [51] M. M. Davis, “A Prescription for Human Immunology,” Health, vol. 27, no. 4, pp. 664–672, 1996. Immunity, vol. 29, no. 6, pp. 835–838, 2008. [37] W. Jampangern, K. Vongthoung, A. Jittmittraphap et al., [52] J. Mestas and C. C. W. Hughes, “Of Mice and Not Men: dif- “Characterization of atypical lymphocytes and immunophe- ferences between mouse and human immunology,” Journal of notypes of lymphocytes in patients with dengue virus Immunology, vol. 172, no. 5, pp. 2731–2738, 2004. infection,” Asian Pacific Journal of Allergy and Immunology, [53] K. Yang, A. Puel, S. Zhang et al., “Human TLR-7-, -8-, and vol. 25, no. 1, pp. 27–36, 2007. -9-mediated induction of IFN-alpha/beta and -lambda Is [38] S. Boonpucknavig, C. Lohachitranond, and S. Nimmanitya, IRAK-4 dependent and redundant for protective immunity “The pattern and nature of the lymphocyte population to viruses,” Immunity, vol. 23, no. 5, pp. 465–478, 2005. response in dengue hemorrhagic fever,” The American Jour- [54] E. Boilard, P. A. Nigrovic, K. Larabee et al., “Platelets nal of Tropical Medicine & Hygiene, vol. 28, no. 5, pp. 885– amplify inflammation in arthritis via collagen-dependent 889, 1979. microparticle production,” Science, vol. 327, no. 5965, pp. [39] R. A. Wells, R. Scott McN., and K. Pavanand, “Kinetics of 580–583, 2010. peripheral blood leukocyte alterations in Thai children with [55] R. W. Faint, “Platelet-neutrophil interactions: their signifi- dengue hemorrhagic fever,” Infection and Immunity, vol. 28, cance,” Blood Reviews, vol. 6, no. 2, pp. 83–91, 1992. no. 2, pp. 428–433, 1980. [56] M. P. Gawaz, S. K. Mujais, B. Schmidt, and H. J. Gurland, [40] L. A. J. O’Neill, “Therapeutic targeting of Toll-like receptors “Platelet-leukocyte aggregation during hemodialysis,” Kidney for inflammatory and infectious diseases,” Current Opinion International, vol. 46, no. 2, pp. 489–495, 1994. in Pharmacology, vol. 3, no. 4, pp. 396–403, 2003. [57] S. Reuter and D. Lang, “Life span of monocytes and platelets: [41] N. Bechetoille, V. Andre, ´ J. Valladeau, E. Perrier, and C. importance of interactions,” Frontiers in Bioscience, vol. 14, Dezutter-Dambuyant, “Mixed Langerhans cell and intersti- pp. 2432–2447, 2009. tial/dermal dendritic cell subsets emanating from mono- [58] H. M. Rinder,J.L.Bonan,C.S.Rinder,K.A.Ault, and cytes in Th2-mediated inflammatory conditions respond B. R. Smith, “Activated and unactivated platelet adhesion to differently to proinflammatory stimuli,” Journal of Leukocyte monocytes and neutrophils,” Blood, vol. 78, no. 7, pp. 1760– Biology, vol. 80, no. 1, pp. 45–58, 2006. 1769, 1991. [42] L. De Witte, A. Nabatov, M. Pion et al., “Langerin is a natural [59] G. Bazzoni, E. Dejana, and A. Del Maschio, “Platelet- barrier to HIV-1 transmission by Langerhans cells,” Nature neutrophil interactions. Possible relevance in the pathogene- Medicine, vol. 13, no. 3, pp. 367–371, 2007. sis of thrombosis and inflammation,” Haematologica, vol. 76, [43] L. de Witte, A. Nabatov, and T. B. H. Geijtenbeek, “Distinct no. 6, pp. 491–499, 1991. roles for DC-SIGN+-dendritic cells and Langerhans cells in [60] B. K. Aikat, “Pathology of mosquito-borne haemorrhagic HIV-1 transmission,” Trends in Molecular Medicine, vol. 14, fever in the Calcutta outbreak,” Bull World Health Organ, vol. no. 1, pp. 12–19, 2008. 35, pp. 48–49, 1966. [44] K. Nagao, F. Ginhoux, W. W. Leitner et al., “Murine [61] E. R. Nelson, H. R. Bierman, and R. Chulajata, “Hematologic epidermal Langerhans cells and langerin-expressing dermal dendritic cells are unrelated and exhibit distinct functions,” findings in the 1960 hemorrhagic fever epidemic (dengue) in Thailand,” The American Journal of Tropical Medicine & Proceedings of the National Academy of Sciences of the United States of America, vol. 106, no. 9, pp. 3312–3317, 2009. Hygiene, vol. 13, pp. 642–649, 1964. [45] R. M. Gordon and W. H. R. Lumsden, “A study of the [62] E. R. Nelson, H. R. Bierman, and R. Chulajata, “Hemato- behaviour of the mouth-parts of mosquitoes when taking up logic phagocytosis in postmortem bone marrows of dengue blood from living tissues; together with some observations hemorrhagic fever. (Hematologic phagocytosis in Thai hem- on the ingestion of microfilariae,” Annals of Tropical Medicine orrhagic fever),” American Journal of the Medical Sciences, vol. and Parasitology, vol. 33, pp. 259–278, 1939. 252, no. 1, pp. 68–74, 1966. 12 Advances in Virology [63] N. J. Marchette, S. B. Halstead, and W. A. Falkler Jr., “Studies pre-existing specific antibodies,” Journal of Medical Virology, on the pathogenesis of dengue infection in monkeys. III. vol. 54, no. 3, pp. 210–218, 1998. Sequential distribution of virus in primary and heterologous [78] S. Honda, M. Saito, E. M. Dimaano et al., “Increased phago- infections,” Journal of Infectious Diseases, vol. 128, no. 1, pp. cytosis of platelets from patients with secondary dengue virus 23–30, 1973. infection by human macrophages,” The American Journal of Tropical Medicine & Hygiene, vol. 80, no. 5, pp. 841–845, [64] N. Onlamoon, S. Noisakran, H.-M. Hsiao et al., “Dengue virus—induced hemorrhage in a nonhuman primate model,” Blood, vol. 115, no. 9, pp. 1823–1834, 2010. [79] P. Marianneau, A.-M. Steffan, C. Royer et al., “Infection of primary cultures of human Kupffer cells by dengue virus: no [65] N. J. Marchette, J. S. Sung Chow, and S. B. Halstead, “Dengue viral progeny synthesis, but cytokine production is evident,” virus replication in cultures of peripheral blood leukocytes Journal of Virology, vol. 73, no. 6, pp. 5201–5206, 1999. during the course of Dengue haemorrhagic fever,” Southeast [80] J. A. Mosquera, J. P. Hernandez, N. Valero, L. M. Espina, and Asian Journal of Tropical Medicine and Public Health, vol. 6, G. J. Anez, ˜ “Ultrastructural studies on dengue virus type 2 no. 3, pp. 316–321, 1975. infection of cultured human monocytes,” Virology Journal, [66] N. J. Marchette, S. B. Halstead, and J. S. Chow, “Replication vol. 2, article 26, 2005. of dengue viruses in cultures of peripheral blood leukocytes [81] K. Fink, C. Ng, C. Nkenfou, S. G. Vasudevan, N. Van from dengue immune rhesus monkeys,” Journal of Infectious Rooijen, and W. Schul, “Depletion of macrophages in mice Diseases, vol. 133, no. 3, pp. 274–282, 1976. results in higher dengue virus titers and highlights the [67] N. Bhamarapravati, P. Tuchinda, and V. Boonyapaknavik, role of macrophages for virus control,” European Journal of “Pathology of Thailand haemorrhagic fever: a study of 100 Immunology, vol. 39, no. 10, pp. 2809–2821, 2009. autopsy cases,” Annals of Tropical Medicine and Parasitology, [82] A. E. Calvert, C. Y.-H. Huang, R. M. Kinney, and J. T. Roehrig, vol. 61, no. 4, pp. 500–510, 1967. “Non-structural proteins of dengue 2 virus offer limited [68] F. C. de Macedo,A.F.Nicol, L. D. Cooper,M.Yearsley,A. protection to interferon-deficient mice after dengue 2 virus R. Cordovil Pires, andG.J.Nuovo,“Histologic, viral, and challenge,” Journal of General Virology, vol. 87, no. 2, pp. 339– molecular correlates of dengue fever infection of the liver 346, 2006. using highly sensitive immunohistochemistry,” Diagnostic [83] M. S. Diamond, T. G. Roberts, D. Edgil, B. Lu, J. Ernst, and E. Molecular Pathology, vol. 15, no. 4, pp. 223–228, 2006. Harris, “Modulation of dengue virus infection in human cells [69] S. B. Halstead and E. J. O’Rourke, “Antibody enhanced by alpha, beta, and gamma interferons,” Journal of Virology, dengue virus infection in primate leukocytes,” Nature, vol. vol. 74, no. 11, pp. 4957–4966, 2000. 265, no. 5596, pp. 739–741, 1977. [84] M. O. Diaz, S. Ziemin, M. M. Le Beau et al., “Homozygous [70] S. B. Halstead, “Observations related to pathogensis of deletion of the α-and β1-interferon genes in human dengue hemorrhagic fever. VI. Hypotheses and discussion,” leukemia and derived cell lines,” Proceedings of the National Yale Journal of Biology and Medicine, vol. 42, no. 5, pp. 350– Academy of Sciences of the United States of America, vol. 85, 362, 1970. no. 14, pp. 5259–5263, 1988. [71] A. C. Eaves, J. D. Cashman, and L. A. Gaboury, “Unregulated [85] M. O. Diaz, C. M. Rubin, A. Harden et al., “Deletions of proliferation of primitive chronic myeloid leukemia pro- interferon genes in acute lymphoblastic leukemia,” The New genitors in the presence of normal marrow adherent cells,” England Journal of Medicine, vol. 322, no. 2, pp. 77–82, 1990. Proceedings of the National Academy of Sciences of the United [86] S. Einhorn, D. Grander, O. Bjork, K. Brondum-Nielsen, States of America, vol. 83, no. 14, pp. 5306–5310, 1986. andS.Soderhall,“Deletion of falpha-, beta-, andomega- [72] S. Blackley, Z. Kou, H. Chen et al., “Primary Human splenic interferon genes in malignant cells from children with acute macrophages, but not T or B cells, are the principal target lymphocytic leukemia,” Cancer Research, vol. 50, no. 24, pp. cells for dengue virus infection in vitro,” Journal of Virology, 7781–7785, 1990. vol. 81, no. 24, pp. 13325–13334, 2007. [87] C. D. James, J. He,E.Carlbom,M.Nordenskjold,W.K. [73] K.-J. Huang, Y.-C. Yang, Y.-S. Lin et al., “The dual-specific Cavenee, and V. P. Collins, “Chromosome 9 deletion map- binding of dengue virus and target cells for the antibody- ping reveals interferon α and interferon β-1 gene deletions dependent enhancement of dengue virus infection,” Journal in human glial tumors,” Cancer Research, vol. 51, no. 6, pp. of Immunology, vol. 176, no. 5, pp. 2825–2832, 2006. 1684–1688, 1991. [74] S. C. Kliks, A. Nisalak, W. E. Brandt, L. Wahl, and D. S. Burke, [88] J. Miyakoshi, K. D. Dobler, J. Allalunis-Turner et al., “Absence “Antibody-dependent enhancement of dengue virus growth of IFNA and IFNB genes from human malignant glioma in human monocytes as a risk factor for dengue hemorrhagic cell lines and lack of correlation with cellular sensitivity to fever,” The American Journal of Tropical Medicine & Hygiene, interferons,” Cancer Research, vol. 50, no. 2, pp. 278–283, vol. 40, no. 4, pp. 444–451, 1989. [75] L. M. Espina, N. J. Valero, J. M. Hernandez, ´ and J. A. [89] J. Fink, F. Gu, L. Ling et al., “Host gene expression profiling Mosquera, “Increased apoptosis and expression of tumor of dengue virus infection in cell lines and patients,” PLoS necrosis factor-α caused by infection of cultured human Neglected Tropical Diseases, vol. 1, no. 2, article e86, 2007. monocytes with dengue virus,” The American Journal of [90] I. Kurane, J. Janus, and F. A. Ennis, “Dengue virus infection Tropical Medicine & Hygiene, vol. 68, no. 1, pp. 48–53, 2003. of human skin fibroblasts in vitro production of IFN-β,IL- [76] T. Hase, P. L. Summers, and K. H. Eckels, “Flavivirus entry 6and GM-CSF,” Archives of Virology, vol. 124, no. 1-2, pp. into cultured mosquito cells and human peripheral blood 21–30, 1992. monocytes,” Archives of Virology, vol. 104, no. 1-2, pp. 129– [91] I. Kurane, B. L. Innis, S. Nimmannitya, A. Nisalak, A. Meager, 143, 1989. and F. A. Ennis, “High levels of interferon alpha in the sera of [77] D. Hober, T. L. Nguyen, L. Shen et al., “Tumor necrosis factor children with dengue virus infection,” The American Journal alpha levels in plasma and whole-blood culture in dengue- of Tropical Medicine & Hygiene, vol. 48, no. 2, pp. 222–229, infected patients: relationship between virus detection and 1993. Advances in Virology 13 [92] C. A. Sariol, J.L. Muno ˜ z-Jordan, K. Abel et al., “Transcrip- Journal of Tropical Medicine & Hygiene,vol. 52, no.5,pp. tional activation of interferon-stimulated genes but not of 468–476, 1995. cytokine genes after primary infection of rhesus macaques [110] S. B. Halstead, “In vivo enhancement of Dengue virus infec- with dengue virus type 1,” Clinical and Vaccine Immunology, tion in rhesus monkeys by passively transferred antibody,” vol. 14, no. 6, pp. 756–766, 2007. Journal of Infectious Diseases, vol. 140, no. 4, pp. 527–533, [93] D. A. Bente and R. Rico-Hesse, “Models of dengue virus infection,” Drug Discovery Today: Disease Models, vol. 3, no. [111] N. J. Marchette and S. B. Halstead, “Immunopathogenesis 1, pp. 97–103, 2006. of dengue infection in the rhesus monkey,” Transplantation [94] L. E. Yauch and S. Shresta, “Mouse models of dengue virus Proceedings, vol. 6, no. 2, pp. 197–201, 1974. infection and disease,” Antiviral Research, vol. 80, no. 2, pp. [112] L. Rosen, “Experimental infection of New World monkeys 87–93, 2008. with dengue and yellow fever viruses,” The American Society [95] H.-C. Chen, S.-Y. Lai, J.-M. Sung et al., “Lymphocyte acti- of Tropical Medicine & Hygiene, vol. 7, no. 4, pp. 406–410, vation and hepatic cellular infiltration in immunocompetent mice infected by dengue virus,” JournalofMedical Virology, [113] A. Rudnick, N. J. Marchette, and R. Garcia, “Possible jungle vol. 73, no. 3, pp. 419–431, 2004. dengue—recent studies and hypotheses,” Japanese Journal of [96] M. V. Paes,A.T.Pinhao, D. F. Barreto et al., “Liver injury and Medical Science and Biology, vol. 20, pp. 69–74, 1967. viremia in mice infected with dengue-2 virus,” Virology, vol. [114] J. S. Simmons, J. H. St. John, and F. H. K. Reynolds, “Exper- 338, no. 2, pp. 236–246, 2005. imental studies of dengue,” Philippine Journal of Science, vol. [97] J. R. Paul, J. L. Melnick, and A. B. Sabin, “Experimental 44, pp. 1–252, 1931. attempts to transmit phlebotomus and dengue fevers to [115] R. H. Whitehead, V. Chaicumpa, L. C. Olson, and P. K. chimpanzees,” Proceedings of The Society for Experimental Russell, “Sequential dengue virus infections in the white- Biology and Medicine, vol. 68, no. 1, pp. 193–198, 1948. handed gibbon (Hylobates lar),” The American Journal of [98] A. B. Sabin, “Research on dengue during World War II,” The Tropical Medicine & Hygiene, vol. 19, no. 1, pp. 94–102, 1970. American Journal of Tropical Medicine & Hygiene, vol. 1, no. [116] F. Guirakhoo, K. Pugachev, J. Arroyo et al., “Viremia and 1, pp. 30–50, 1952. [99] S.-T. Chen, Y.-L. Lin, M.-T. Huang et al., “CLEC5A is critical immunogenicity in nonhuman primates of a tetravalent yel- low fever-dengue chimeric vaccine: genetic reconstructions, for dengue-virus-induced lethal disease,” Nature, vol. 453, dose adjustment, and antibody responses against wild-type no. 7195, pp. 672–676, 2008. dengue virus isolates,” Virology, vol. 298, no. 1, pp. 146–159, [100] Y.-H. Huang, H.-Y. Lei, H.-S. Liu, Y.-S. Lin, C.-C. Liu, and T.- M. Yeh, “Dengue virus infects human endothelial cells and induces IL-6 and IL-8 production,” The American Journal [117] B. Guy, V. Barban, N. Mantel et al., “Evaluation of interfer- of Tropical Medicine & Hygiene, vol. 63, no. 1-2, pp. 71–75, ences between dengue vaccine serotypes in a monkey model,” The American Journal of Tropical Medicine & Hygiene, vol. 80, [101] A. J. Johnson and J. T. Roehrig, “New mouse model for no. 2, pp. 302–311, 2009. dengue virus vaccine testing,” Journal of Virology, vol. 73, no. [118] P. Koraka, S. Benton, G. V. Amerongen, K. J. Stittelaar, and 1, pp. 783–786, 1999. A. D. M. E. Osterhaus, “Characterization of humoral and [102] S. Shresta, K. L. Sharar, D. M. Prigozhin, P. R. Beatty, cellular immune responses in cynomolgus macaques upon and E. Harris, “Murine model for dengue virus-induced primary and subsequent heterologous infections with dengue lethal disease with increased vascular permeability,” Journal viruses,” Microbes and Infection, vol. 9, no. 8, pp. 940–946, of Virology, vol. 80, no. 20, pp. 10208–10217, 2006. [103] J. An, J. Kimura-Kuroda, Y. Hirabayashi, and K. Yasui, [119] J. Velzing, J. Groen, M. T. Drouet et al., “Induction of pro- “Development of a novel mouse model for dengue virus tective immunity against dengue virus type 2: comparison infection,” Virology, vol. 263, no. 1, pp. 70–77, 1999. of candidate live attenuated and recombinant vaccines,” [104] D. A. Bente, M. W. Melkus, J. V. Garcia, and R. Rico-Hesse, Vaccine, vol. 17, no. 11-12, pp. 1312–1320, 1999. “Dengue fever in humanized NOD/SCID mice,” Journal of [120] J. Stasney and G. M. Higgins, “Bone marrow in the monkey Virology, vol. 79, no. 21, pp. 13797–13799, 2005. (macacus rhesus),” The Anatomical Record,vol. 67, no.2,pp. [105] J. E. Blaney Jr., D. H. Johnson, G. G. Manipon et al., “Genetic 219–231, 1973. basis of attenuation of dengue virus type 4 small plaque [121] L. Wills and A. Stewart, “Experimental Anaemia in monkeys, mutants with restricted replication in suckling mice and in with special reference to macrocytic nutritional anaemia,” SCID mice transplanted with human liver cells,” Virology, British Journal of Experimental Pathology, vol. 16, pp. 444– vol. 300, no. 1, pp. 125–139, 2002. 453, 1935. [106] J. G. Kuruvilla, R. M. Troyer, S. Devi, and R. Akkina, “Dengue [122] T. Kushida, M. Inaba, K. Ikebukuro et al., “Comparison of virus infection and immune response in humanized RAG2-/- bone marrow cells harvested from various bones of cynomol- γc-/- (RAG-hu) mice,” Virology, vol. 369, no. 1, pp. 143–152, gusmonkeys at variousagesbyperfusion or aspiration methods: a preclinical study for human BMT,” Stem Cells, vol. [107] Y.-L. Lin, C.-L. Liao, L.-K. Chen et al., “Study of dengue virus 20, no. 2, pp. 155–162, 2002. infection in SCID mice engrafted with human K562 cells,” [123] H. R. Bierman and E. R. Nelson, “Hematodepressive virus Journal of Virology, vol. 72, no. 12, pp. 9729–9737, 1998. diseases of Thailand,” Annals of Internal Medicine, vol. 62, pp. [108] J. Mota and R. Rico-Hesse, “Humanized mice show clinical 867–884, 1965. signs of dengue fever according to infecting virus genotype,” Journal of Virology, vol. 83, no. 17, pp. 8638–8645, 2009. [124] S. Na-Nakorn, A. Suingdumrong, S. Pootrakul, and N. [109] S.-J. L. Wu, C. G. Hayes, D. R. Dubois et al., “Evaluation Bhamarapravati, “Bone-marrow studies in Thai haemor- of the severe combined immunodeficient (SCID) mouse as rhagic fever,” Bull World Health Organ, vol. 35, no. 17, pp. an animal model for dengue viral infection,” The American 54–55, 1966. 14 Advances in Virology [125] E. R. Nelson and H. R. Bierman, “Dengue fever: a thrombo- [142] K. Jurk and B. E. Kehrel, “Platelets: physiology and biochem- cytopenic disease?” Journal of the American Medical Associa- istry,” Seminars in Thrombosis and Hemostasis,vol. 31, no.4, tion, vol. 190, pp. 99–103, 1964. pp. 381–392, 2005. [126] E. R. Nelson, S. Tuchinda, H. R. Bierman, and R. Chulajata, [143] Z. M. Ruggeri, “Platelets in atherothrombosis,” Nature “Haematology of Thai haemorrhagic fever (dengue),” Bull Medicine, vol. 8, no. 11, pp. 1227–1234, 2002. World Health Organ, vol. 35, pp. 43–44, 1966. [144] J. H. Hartwig, “The platelet: form and function,” Seminars in [127] K. Oishi, M. Saito, C. A. Mapua, and F. F. Natividad, “Dengue Hematology, vol. 43, no. 1, pp. S94–S100, 2006. illness: clinical features and pathogenesis,” Journal of Infection [145] R. K. Andrews and M. C. Berndt, “Platelet physiology and and Chemotherapy, vol. 13, no. 3, pp. 125–133, 2007. thrombosis,” Thrombosis Research, vol. 114, no. 5-6, pp. 447– [128] K. I. Schexneider and E. A. Reedy, “Thrombocytopenia in 453, 2004. dengue fever,” Current Hematology Reports,vol. 4, no.2,pp. [146] K. Kaushansky, “Historical review: megakaryopoiesis and 145–148, 2005. thrombopoiesis,” Blood, vol. 111, no. 3, pp. 981–986, 2008. [129] T. Srichaikul and S. Nimmannitya, “Haematology in dengue [147] F. Rendu and B. Brohard-Bohn, “The platelet release reac- anddenguehaemorrhagicfever,” Bailliere’s Best Practice and tion: granules’ constituents, secretion and functions,” Research in Clinical Haematology, vol. 13, no. 2, pp. 261–276, Platelets, vol. 12, no. 5, pp. 261–273, 2001. [148] J. E. Italiano Jr., P. Lecine, R. A. Shivdasani, and J. H. [130] M. Saito, K. Oishi, S. Inoue et al., “Association of increased Hartwig, “Blood platelets are assembled principally at the platelet-associated immunoglobulins with thrombocytope- ends of proplatelet processes produced by differentiated nia and the severity of disease in secondary dengue virus megakaryocytes,” Journal of Cell Biology, vol. 147, no. 6, pp. infections,” Clinical and Experimental Immunology, vol. 138, 1299–1312, 1999. no. 2, pp. 299–303, 2004. [149] S. R. Patel, J. H. Hartwig, and J. E. Italiano Jr., “The biogenesis [131] S. Noisakran and C. P. Guey, “Alternate hypothesis on the of platelets from megakaryocyte proplatelets,” Journal of pathogenesis of dengue hemorrhagic fever (DHF)/dengue Clinical Investigation, vol. 115, no. 12, pp. 3348–3354, 2005. shock syndrome (DSS) in dengue virus infection,” Experi- [150] W. N. Erber, A. Jacobs, D. G. Oscier, A. M. O’Hea, and D. Y. mental Biology and Medicine, vol. 233, no. 4, pp. 401–408, Mason, “Circulating micromegakaryocytes in myelodyspla- sia,” Journal of Clinical Pathology, vol. 40, no. 11, pp. 1349– [132] S. Noisakran, K. Chokephaibulkit, P. Songprakhon et al., “A 1352, 1987. re-evaluation of the mechanisms leading to dengue hemor- [151] S. Boukour, J.-M. Masse, ´ L. Benit, ´ A. Dubart-Kupperschmitt, rhagic fever,” Annals of the New York Academy of Sciences, vol. and E. M. Cramer, “Lentivirus degradation and DC-SIGN 1171, supplement 1, pp. E24–E35, 2009. expression by human platelets and megakaryocytes,” Journal [133] S. Noisakran, R. V. Gibbons, P. Songprakhon et al., “Detec- of Thrombosis and Haemostasis, vol. 4, no. 2, pp. 426–435, tion of dengue virus in platelets isolated from dengue patients,” Southeast Asian Journal of Tropical Medicine and [152] C. L. Anderson, G. W. Chacko, J. M. Osborne, and J. T. Public Health, vol. 40, no. 2, pp. 253–262, 2009. Brandt, “The Fc receptor for immunoglobulin G (FcγRII) [134] R. Flaumenhaft, J. R. Dilks, J. Richardson et al., “Meg- on human platelets,” Seminars in Thrombosis and Hemostasis, akaryocyte-derived microparticles: direct visualization and vol. 21, no. 1, pp. 1–9, 1995. distinction from platelet-derived microparticles,” Blood, vol. [153] C. Skoglund, J. Wettero, ¨ T. Skogh, C. Sjowal ¨ l, P. Tengvall, and 113, no. 5, pp. 1112–1121, 2009. T. Bengtsson, “C-reactive protein and C1q regulate platelet [135] N. Bhamarapravati, V. Boonyapaknavik, and P. Nimsombu- adhesion and activation on adsorbed immunoglobulin G and rana, “Pathology of Thai haemorrhagic fever: an autopsy albumin,” Immunology and Cell Biology, vol. 86, no. 5, pp. study,” Bull WorldHealthOrgan, vol. 35, pp. 47–48, 1966. 466–474, 2008. [136] J. B. Gorius, B. Dreyfus, C. Sultan, A. Basch, and J. G. [154] M. J. Woods, M. Greaves, and E. A. Trowbridge, “The d’Oliveira, “Identification of circulating micromegakaryo- physiological significance of circulating megakaryocytes,” cytes in a case of refractory anemia: an electron microscopic- British Journal of Haematology, vol. 80, no. 2, pp. 266–267, cytochemical study,” Blood, vol. 40, no. 4, pp. 453–463, 1972. 1992. [137] K. Yamauchi, J. Miyauchi, and T. Nagao, “Identification of [155] P. E. Stenberg and J. Levin, “Mechanisms of platelet produc- circulating micromegakaryocytes in a case of erythroleuke- tion,” Blood Cells, vol. 15, no. 1, pp. 23–47, 1989. mia,” Cancer, vol. 53, no. 12, pp. 2668–2673, 1984. [156] J. M. Radley and C. J. Haller, “Fate of senescent megakary- [138] M. M. Denis, N. D. Tolley, M. Bunting et al., “Escaping ocytes in thebonemarrow,” British Journal of Haematology, the nuclear confines: signal-dependent pre-mRNA splicing in vol. 53, no. 2, pp. 277–287, 1983. anucleate platelets,” Cell, vol. 122, no. 3, pp. 379–391, 2005. [157] P. G. Fuhrken, C. Chen, W. M. Miller, and E. T. Papout- [139] H. Schwertz, N. D. Tolley, J. M. Foulks et al., “Signal- sakis, “Comparative, genome-scale transcriptional analysis dependent splicing of tissue factor pre-mRNA modulates the of CHRF-288-11 and primary human megakaryocytic cell thrombogenecity of human platelets,” Journal of Experimen- cultures provides novel insights into lineage-specific differ- tal Medicine, vol. 203, no. 11, pp. 2433–2440, 2006. entiation,” Experimental Hematology, vol. 35, no. 3, pp. 476– 489, 2007. [140] H. Schwertz, S. Kost ¨ er, W. H. Kahr et al., “Anucleate platelets generate progeny,” Blood, vol. 115, no. 18, pp. 3801–3809, [158] J.-A. Kim, Y.-J. Jung, J.-Y. Seoh, S.-Y. Woo, J.-S. Seo, and 2010. H.-L. Kim, “Gene expression profile of megakaryocytes from human cord blood CD34+ cells ex vivo expanded by [141] E. M. Dimaano, M. Saito, S. Honda et al., “Lack of efficacy of thrombopoietin,” Stem Cells, vol. 20, no. 5, pp. 402–416, high-dose intravenous immunoglobulin treatment of severe thrombocytopenia in patients with secondary dengue virus infection,” The American Journal of Tropical Medicine & [159] N. Bhamarapravati, S. B.. Halstead, P. Sookavachana, and Hygiene, vol. 77, no. 6, pp. 1135–1138, 2007. V. Boonyapaknavik, “Studies on dengue virus infection. Advances in Virology 15 1. immunofluorescent localization of virus in mouse tissue,” Archives of Pathology, vol. 77, pp. 538–543, 1964. [160] V. M. Reyes, “The pathology of haemorrhagic fever in the Philippines,” Bull World Health Organ, vol. 35, pp. 49–50, [161] N. Bhamarapravati, “The spectrum of pathological changes in Thai haemorrhagic fever,” SEATO Medical Research Mono- graph, vol. 2, pp. 76–80, 1961. [162] P. Piyaratn, “Pathology of Thailand epidemic hemorrhagic fever,” The American Journal of Tropical Medicine & Hygiene, vol. 10, pp. 767–772, 1961. International Journal of Peptides Advances in International Journal of BioMed Stem Cells Virolog y Research International International Genomics Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 Journal of Nucleic Acids International Journal of Zoology Hindawi Publishing Corporation Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 Submit your manuscripts at http://www.hindawi.com The Scientific Journal of Signal Transduction World Journal Hindawi Publishing Corporation Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 International Journal of Advances in Genetics Anatomy Biochemistry Research International Research International Microbiology Research International Bioinformatics Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 Enzyme Journal of International Journal of Molecular Biology Archaea Research Evolutionary Biology International Marine Biology Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation Hindawi Publishing Corporation http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014 http://www.hindawi.com Volume 2014

Journal

Advances in VirologyHindawi Publishing Corporation

Published: Aug 12, 2010

There are no references for this article.