We found that CRF07_BC infected patients exhibited lower risk of disease progression to immunodeficiency, i.e. CD4 cell count < 200 cells/ml and lower immunodeficiency incidence compared to those infected with HIV-1 subtype B or CRF01_AE while the period from HIV-1 diagnosis to the occurrence of immunodeficiency was significantly longer for CRF07_BC than CRF55_01B and CRF01_AE (2, 9, –, 11). Here, CD4 is linked to immunodeficiency disease.