Abstract

Optimization of the Cutoff Value for a Commercial Anti-Dengue Virus IgG Immunoassay Karla M. Marrero-Santos a , Manuela Beltrán a , Jessica Carrión-Lebrón a , Carolina Sanchez-Vegas b , Davidson H. Hamer c , Elizabeth D. Barnett d , Luis M. Santiago a and Elizabeth A. Hunsperger a a Dengue Branch, Division of Vector-Borne Diseases, Centers For Disease Control and Prevention, San Juan, Puerto Rico b Miami Children's Hospital, Pediatric Infectious Diseases, Miami, Florida, USA c Center for Global Health and Development, Department of International Health, School of Public Health, and Section of Infectious Diseases, Department of Medicine, School of Medicine, Boston University, Boston, Massachusetts, USA d Maxwell Finland Laboratory for Infectious Diseases, Boston Medical Center, Boston, Massachusetts, USA ABSTRACT A commercial anti-dengue virus (anti-DENV) indirect IgG enzyme-linked immunosorbent assay (ELISA) for serological diagnosis was evaluated for its utility in determining previous DENV exposure in U.S. travelers. The Boston Area Travel Medicine Network clinics used Focus Diagnostics anti-DENV IgG ELISA to measure anti-DENV IgG antibodies in 591 pretravel specimens from U.S. residents who had traveled to countries where dengue is endemic. When using the manufacturer's index cutoff value for this ELISA, false-positive results were observed that overestimated the perceived past DENV exposure in U.S. travelers. Validation of 121 of these anti-DENV IgG results by plaque reduction neutralization test (PRNT) was used for receiver operating characteristic (ROC) curve optimization of the index cutoff value from 1 to 3.0, improving the specificity of the anti-DENV IgG ELISA from 24% to 95.7%. Additionally, previous vaccination with yellow fever virus contributed to 52.8% of the false-positive rate in the anti-DENV IgG ELISA results. Optimization of the cutoff value of the anti-DENV IgG ELISA provided better interpretation and confidence in the results and eliminated the need for confirmation by PRNT. The travel history of U.S. travelers was also useful for categorizing these travelers into groups for analysis of previous DENV exposure.