Additionally, the upregulation of CTLA-4 in CD4+ T-cells was reported to cause a high level of CCR5 expression on CD4+ T-cells, thereby supporting a vigorous HIV-1 infection [48], which suggests that CTLA-4 upregulation by HIV infection could increase CD4+ T-cell susceptibility to HIV infection. The gene discussed is CD4; the disease is HIV-1 infection.