Sequence Conservation and Antibody Cross- Recognition of Clade B Human Immunodeficiency Virus (HIV) Type 1 Tat Protein in HIV-1–Infected

We determined immune cross-recognition and the degree of Tat conservation in patients infected by local human immunodeficiency virus (HIV) type 1 strains. The data indicated a similar prevalence of total and epitope-specific anti–Tat IgG in 578 serum samples from HIV-infected Italian (), Ugandan (),np 302 np 139 and South African ( ) subjects, using the same B clade Tat protein that is being used in vaccine trials.np 137 In particular, anti-Tat antibodies were detected in 13.2%, 10.8%, and 13.9 % of HIV-1–infected individuals from Italy, Uganda, and South Africa, respectively. Sequence analysis results indicated a high similarity of Tat from the different circulating viruses with BH-10 Tat, particularly in the 1–58 amino acid region, which contains most of the immunogenic epitopes. These data indicate an effective cross-recognition of a B-clade laboratory strain–derived Tat protein vaccine by individuals infected with different local viruses, owing to the high similarity of Tat epitopes. The development of a vaccine against human immu-nodeficiency virus (HIV) or AIDS that is capable of inducing sterilizing immunity has been hampered by the extreme cross-clade variability of the HIV envelope (Env) protein and by the incapacity of Env-based vac