TLR7KO mice infected with EV71 showed significantly reduced IgG2a/c, IgG2b and IgM while increased IgG1 and IgG3 as compared with WT mice, suggesting that TLR7 play a critical role in humoral immunity to EV71 infection by generating Th1 associated antibodies- IgG2a/c and IgG2b, important for host defense to viral infection. The gene discussed is IGHG3; the disease is viral infectious disease.