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

Learn More →

Direct Neutralization of Type III Effector Translocation by the Variable Region of a Monoclonal Antibody to Yersinia pestis LcrV

Direct Neutralization of Type III Effector Translocation by the Variable Region of a Monoclonal... Direct Neutralization of Type III Effector Translocation by the Variable Region of a Monoclonal Antibody to Yersinia pestis LcrV Maya I. Ivanov a , Jim Hill b and James B. Bliska a a Department of Molecular Genetics and Microbiology, Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, USA b Defence Science and Technology Laboratory, Porton Down, United Kingdom D. L. Burns , Editor ABSTRACT Plague is an acute infection caused by the Gram-negative bacterium Yersinia pestis . Antibodies that are protective against plague target LcrV, an essential virulence protein and component of a type III secretion system of Y. pestis . Secreted LcrV localizes to the tips of type III needles on the bacterial surface, and its function is necessary for the translocation of Yersinia outer proteins (Yops) into the cytosol of host cells infected by Y. pestis . Translocated Yops counteract macrophage functions, for example, by inhibiting phagocytosis (YopE) or inducing cytotoxicity (YopJ). Although LcrV is the best-characterized protective antigen of Y. pestis , the mechanism of protection by anti-LcrV antibodies is not fully understood. Antibodies bind to LcrV at needle tips, neutralize Yop translocation, and promote opsonophagocytosis of Y. pestis by macrophages in vitro . However, it is not clear if anti-LcrV antibodies neutralize Yop translocation directly or if they do so indirectly, by promoting opsonophagocytosis. To determine if the protective IgG1 monoclonal antibody (MAb) 7.3 is directly neutralizing, an IgG2a subclass variant, a deglycosylated variant, F(ab′) 2 , and Fab were tested for the ability to inhibit the translocation of Yops into Y. pestis -infected macrophages in vitro . Macrophage cytotoxicity and cellular fractionation assays show that the Fc of MAb 7.3 is not required for the neutralization of YopJ or YopE translocation. In addition, the use of Fc receptor-deficient macrophages, and the use of cytochalasin D to inhibit actin polymerization, confirmed that opsonophagocytosis is not required for MAb 7.3 to neutralize translocation. These data indicate that the binding of the variable region of MAb 7.3 to LcrV is sufficient to directly neutralize Yop translocation. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Clinical and Vaccine Immunology American Society For Microbiology

Direct Neutralization of Type III Effector Translocation by the Variable Region of a Monoclonal Antibody to Yersinia pestis LcrV

Direct Neutralization of Type III Effector Translocation by the Variable Region of a Monoclonal Antibody to Yersinia pestis LcrV

Clinical and Vaccine Immunology , Volume 21 (5): 667 – May 1, 2014

Abstract

Direct Neutralization of Type III Effector Translocation by the Variable Region of a Monoclonal Antibody to Yersinia pestis LcrV Maya I. Ivanov a , Jim Hill b and James B. Bliska a a Department of Molecular Genetics and Microbiology, Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, USA b Defence Science and Technology Laboratory, Porton Down, United Kingdom D. L. Burns , Editor ABSTRACT Plague is an acute infection caused by the Gram-negative bacterium Yersinia pestis . Antibodies that are protective against plague target LcrV, an essential virulence protein and component of a type III secretion system of Y. pestis . Secreted LcrV localizes to the tips of type III needles on the bacterial surface, and its function is necessary for the translocation of Yersinia outer proteins (Yops) into the cytosol of host cells infected by Y. pestis . Translocated Yops counteract macrophage functions, for example, by inhibiting phagocytosis (YopE) or inducing cytotoxicity (YopJ). Although LcrV is the best-characterized protective antigen of Y. pestis , the mechanism of protection by anti-LcrV antibodies is not fully understood. Antibodies bind to LcrV at needle tips, neutralize Yop translocation, and promote opsonophagocytosis of Y. pestis by macrophages in vitro . However, it is not clear if anti-LcrV antibodies neutralize Yop translocation directly or if they do so indirectly, by promoting opsonophagocytosis. To determine if the protective IgG1 monoclonal antibody (MAb) 7.3 is directly neutralizing, an IgG2a subclass variant, a deglycosylated variant, F(ab′) 2 , and Fab were tested for the ability to inhibit the translocation of Yops into Y. pestis -infected macrophages in vitro . Macrophage cytotoxicity and cellular fractionation assays show that the Fc of MAb 7.3 is not required for the neutralization of YopJ or YopE translocation. In addition, the use of Fc receptor-deficient macrophages, and the use of cytochalasin D to inhibit actin polymerization, confirmed that opsonophagocytosis is not required for MAb 7.3 to neutralize translocation. These data indicate that the binding of the variable region of MAb 7.3 to LcrV is sufficient to directly neutralize Yop translocation.

Loading next page...
 
/lp/american-society-for-microbiology/direct-neutralization-of-type-iii-effector-translocation-by-the-oC9t90qp4p

References (49)

Publisher
American Society For Microbiology
Copyright
Copyright © 2014 by the American society for Microbiology.
ISSN
1556-6811
eISSN
1556-679X
DOI
10.1128/CVI.00013-14
pmid
24599533
Publisher site
See Article on Publisher Site

Abstract

Direct Neutralization of Type III Effector Translocation by the Variable Region of a Monoclonal Antibody to Yersinia pestis LcrV Maya I. Ivanov a , Jim Hill b and James B. Bliska a a Department of Molecular Genetics and Microbiology, Center for Infectious Diseases, Stony Brook University, Stony Brook, New York, USA b Defence Science and Technology Laboratory, Porton Down, United Kingdom D. L. Burns , Editor ABSTRACT Plague is an acute infection caused by the Gram-negative bacterium Yersinia pestis . Antibodies that are protective against plague target LcrV, an essential virulence protein and component of a type III secretion system of Y. pestis . Secreted LcrV localizes to the tips of type III needles on the bacterial surface, and its function is necessary for the translocation of Yersinia outer proteins (Yops) into the cytosol of host cells infected by Y. pestis . Translocated Yops counteract macrophage functions, for example, by inhibiting phagocytosis (YopE) or inducing cytotoxicity (YopJ). Although LcrV is the best-characterized protective antigen of Y. pestis , the mechanism of protection by anti-LcrV antibodies is not fully understood. Antibodies bind to LcrV at needle tips, neutralize Yop translocation, and promote opsonophagocytosis of Y. pestis by macrophages in vitro . However, it is not clear if anti-LcrV antibodies neutralize Yop translocation directly or if they do so indirectly, by promoting opsonophagocytosis. To determine if the protective IgG1 monoclonal antibody (MAb) 7.3 is directly neutralizing, an IgG2a subclass variant, a deglycosylated variant, F(ab′) 2 , and Fab were tested for the ability to inhibit the translocation of Yops into Y. pestis -infected macrophages in vitro . Macrophage cytotoxicity and cellular fractionation assays show that the Fc of MAb 7.3 is not required for the neutralization of YopJ or YopE translocation. In addition, the use of Fc receptor-deficient macrophages, and the use of cytochalasin D to inhibit actin polymerization, confirmed that opsonophagocytosis is not required for MAb 7.3 to neutralize translocation. These data indicate that the binding of the variable region of MAb 7.3 to LcrV is sufficient to directly neutralize Yop translocation.

Journal

Clinical and Vaccine ImmunologyAmerican Society For Microbiology

Published: May 1, 2014

There are no references for this article.