A Brazilian Zika virus isolate preferentially induces T follicular helper cell responses while suppressing Th1 immunity

Abstract

Abstract Zika virus (ZIKV) is a mosquito-borne pathogen that caused a series of increasingly severe outbreaks in Micronesia, French Polynesia, and South and Central America. Recent work from our laboratory has shown that, compared to a pre-epidemic isolate (ZIKV-CDN), a Brazilian ZIKV isolate (ZIKV-BR) possesses a novel capacity to suppress antigen-specific CD8 T cell responses, resulting in sustained infection. However, it is unknown whether ZIKV-BR also modulates CD4 T cell immunity. Thus, we investigated the CD4 T cell response to infection with each ZIKV isolate. Our data demonstrate that the CD4 T cell response to ZIKV-BR is reduced in magnitude compared to the response induced by ZIKV-CDN. Further, CD4 T cells are less polarized to the Th1 subtype, express less T-Bet, and are functionally impaired, as they produce less IFN-γ following ex vivo restimulation. Although we observed no alterations in the Th2, Th17 or T regulatory cell compartments, we observed a striking accumulation of PD-1hiCXCR5+ T follicular helper (Tfh) cells 10 days post-infection with ZIKV-BR. This response correlated with an enhanced germinal center B cell response, and increased detection of germinal center formation by confocal microscopy. Future studies will aim to determine the mechanism through which ZIKV-BR infection enhances the Tfh response, and the implications of promoting Tfh responses while dampening Th1 responses for antiviral immunity. Together, our data suggest that contemporary ZIKV strains have evolved to modulate CD4 T cell responses and this could provide a model for interrogating the signals required for Tfh development.