Yellow fever vaccine protects mice against Zika virus infection

Abstract

Zika virus (ZIKV) emerged as an important infectious disease agent in Brazil in 2016. Infection usually leads to mild symptoms, but severe congenital neurological disorders and Guillain-Barré syndrome have been reported following ZIKV exposure. Creating an effective vaccine against ZIKV is a public health priority. We describe the protective effect of an already licensed attenuated yellow fever vaccine (YFV, 17DD) in type-I interferon receptor knockout mice (A129) and immunocompetent BALB/c and SV-129 (A129 background) mice infected with ZIKV. YFV vaccination provided protection against ZIKV, with decreased mortality in A129 mice, a reduction in the cerebral viral load in all mice, and weight loss prevention in BALB/c mice. The A129 mice that were challenged two and three weeks after the first dose of the vaccine were fully protected, whereas partial protection was observed five weeks after vaccination. In all cases, the YFV vaccine provoked a substantial decrease in the cerebral viral load. YFV immunization also prevented hippocampal synapse loss and microgliosis in ZIKV-infected mice. Our vaccine model is T cell-dependent, with AG129 mice being unable to tolerate immunization (vaccination is lethal in this mouse model), indicating the importance of IFN-γ in immunogenicity. To confirm the role of T cells, we immunized nude mice that we demonstrated to be very susceptible to infection. Immunization with YFV and challenge 7 days after booster did not protect nude mice in terms of weight loss and showed partial protection in the survival curve. When we evaluated the humoral response, the vaccine elicited significant antibody titers against ZIKV; however, it showed no neutralizing activity in vitro and in vivo. The data indicate that a cell-mediated response promotes protection against cerebral infection, which is crucial to vaccine protection, and it appears to not necessarily require a humoral response. This protective effect can also be attributed to innate factors, but more studies are needed to strengthen this hypothesis. Our findings open the way to using an available and inexpensive vaccine for large-scale immunization in the event of a ZIKV outbreak.

Peculiarities of Zika Immunity and Vaccine Development: Lessons from Dengue and the Contribution from Controlled Human Infection Model

“…Interestingly, an epidemiological study in Brazil found that ZIKV-related microcephaly was more common in Brazilian regions with the least coverage of YFV vaccination [ 91 ] suggesting a role for cross-reactivity between YFV immunity. In agreement, Vicente et al demonstrated that immunization against YFV using 17DD vaccine can decrease cerebral virus load, prevent neurological manifestations, weight loss and mortality in a fatal murine model of ZIKV infection by mechanisms possibly associated with cross-reactive cell-mediated immunity [ 92 ]. Indeed, YFV vaccination leads to the emergence of ZIKV-specific CD8 T cells [ 93 ].…”

Microcephaly and Associated Risk Factors in Newborns: A Systematic Review and Meta-Analysis Study

“…This situation may favor infectious disease reemergence, a fact recently observed with the reappearance of measles [ 35 ] and yellow fever [ 36 ]. As yellow fever vaccine may confer partial protection against ZIKV [ 37 ], it is likely the poverty–microcephaly relationship be triggered by settings composed of low vaccine coverage.…”