An elegant study by Teo et al. (2017) illustrated the essential role of CD4+ T cells in the CHIKV-induced joint inflammation, as transferring splenic CD4+ T cells from CHIKV-infected wild-type mouse into CHIKV-infected T cell receptor-deficient (Tcr−/−) mice recapitulated severe joint disease (Teo et al., 2017). This evidence concerns the gene CD4 and arthropathy.