HIV-l Subtype b tat gene activities and disease progression in hiv-l CRF01-AE infection

HIV-l tat gene function and immunogenicity of HIV-l Tat protein from 3 low (PS01, PS40, PS58) and 3 high (PS19, PS65, LP22) viral load infected, untreated and asymptomatic individuals from Thailand were compared. Levels of Tat-depen-dent chloramphenicol acetyltransferase (CAT) induced in HL3T1 cells with tail gene from HIV-l isolates of high viral load group was significantly higher than those from low viral load group. HIV-l subtype determination using env (C2-V4) gene demonstrated that 2/3 (PS01 and PS40) and 1/3 (PS58) from low viral load group were CRF01-AE and subtype B, while all 3 HIV-l isolates from high viral load group were CRF01-AE. However, all 3 HIV-l tat nucleotide sequences from low viral load group, which contained env CRF01-AE sequence, belonged to subtype B whereas all those from high viral load group contained CRF01-AE sequence. HIV Tat recombinant proteins from these groups were tested for immunogenicity in mice. All recombinant Tat proteins (except from PS58) were immunogenic in a dose-dependent manner, but with significantly differences of the immunogenicity levels between high and low viral load groups. These results indicated that HIV-l subtype B tat gene activities might be associated with reduced disease progression of HIV-l CRF01-AE infected individuals.