Tfc cells control viral infection in Tfh cells; the frequency of LCMV-infected Tfh cells in mice that have received Cxcr5–/– P14 cells is about twofold higher than that in mice receiving Cxcr5+/+ P14 cells. Tfc cells control viral infection in B cells; the frequency of MuHV-4-infected B cells is about 4.5-fold higher in mice that have received Tc cells than in mice that have received Tfc cells. The gene discussed is CXCR5; the disease is viral infectious disease.