T cell responses to nonstructural protein 3 distinguish infections by Dengue and Zika viruses

Abstract

ABSTRACTThe 2015-16 Zika virus (ZIKV) epidemic in the Americas and the Caribbean demonstrates that clinical assays to detect, distinguish, and characterize immune responses to flaviviral infections are needed. ZIKV and dengue virus (DENV) are mosquito-transmitted flaviviruses sharing overlapping geographical distribution and have significant sequence similarity that can increase the potential for antibody and T cell cross-reaction. Using nonstructural protein 1-based enzyme-linked immunosorbent assays (ELISAs), we determine the serostatus of individuals living in a DENV- and ZIKV-endemic region in Brazil, identifying individuals with primary DENV (pDENV) and ZIKV (pZIKV), ZIKV with primary DENV (ZIKVwpDENV), and secondary DENV (sDENV) infections; pDENV and pZIKV were further confirmed by neutralization tests. Development of an enzyme-linked immunospot (ELISPOT) assay for DENV and ZIKV structural and nonstructural (NS) protein antigens enables us to distinguish infections by these viruses based on T cells and to characterize those responses. We find that IFN-γ and TNF-α T cell responses to NS3 differentiates DENV and ZIKV infections with 94% sensitivity and 92% specificity. In general, we also show that pDENV and sDENV cases and pZIKV and ZIKVwpDENV cases elicit similar T cell response patterns, and that HIV-infected individuals have T cell responses that are lower in magnitude compared to HIV-negative individuals. These results have important implications for DENV and ZIKV diagnostic and vaccine development and provide critical insights into the T cell response in individuals with multiple flaviviral infections.