Adaptive immune responses to Zika virus are important for controlling virus infection and preventing infection in brain and testes

Abstract

Abstract The recent association between Zika virus (ZIKV) and neurological complications including Guillain-Barré Syndrome (GBS) in adults and CNS abnormalities in fetuses highlights the urgency to understand the immunological mechanisms controlling this emerging infection. Studies have indicated that ZIKV evades the human type I IFN response suggesting a role for the adaptive immune response in resolving infection. However, the inability of ZIKV to antagonize the mouse IFN response renders the virus highly susceptible to circulating IFN in murine models. Thus, as we show here, although wild type C57BL/6 mice mount both cell-mediated and humoral adaptive immune responses to ZIKV, these responses were not required to prevent disease. However, when the type I IFN response of mice was suppressed, then the adaptive immune responses became critical. For example, when type I IFN signaling was blocked by antibodies in Rag1−/− immunodeficient mice, the mice showed dramatic weight loss and ZIKV infection in the brain and testes. This phenotype was not observed in Rag1−/− mice or mice treated with anti-IFNAR alone. Furthermore, we found that the CD8+ T cell responses of pregnant mice to ZIKV infection were diminished compared to non-pregnant mice. It is possible that diminished cell-mediated immunity during pregnancy could increase virus spread to the fetus. These results demonstrate an important role for the adaptive immune response in control of ZIKV infection, and imply that vaccination may prevent ZIKV-related disease, particularly when the type I IFN response is suppressed as it is in humans.