With the loss of IFN-γ+ Th1-like Tfh cells, Ifng−/−: Bcl6fl/flCd4-Cre mixed bone marrow chimeras had fewer IgG2c-producing cells and lower level of ZIKV envelope specific IgG2c in sera after ZIKV infection (Fig. 8h, i), suggesting IFN-γ produced by Th1-like Tfh cells is responsible for IgG2 switching. This evidence concerns the gene IFNG and Zika virus infectious disease.