Cytotoxic T-cell responses to HIV-1 reverse transcriptase, integrase and protease.

OBJECTIVES: To determine immunodominant regions and new epitopes for cytotoxic T cells (CTL) directed against the HIV-1 pol products reverse transcriptase (RT), integrase and protease in a large cohort of patients at different stages of disease. DESIGN AND METHODS: Cross-sectional analysis of 98 patients from the French IMMUNOCO cohort (CD4 counts: 125-1050 x 10(6) cells/l), monitored for CTL recognition of HIV-1 pol products using recombinant vaccinia virus constructs and synthetic peptides.
RESULTS: Memory CTL responses against HIV-1 pol products were detected in 78% of all patients whatever the stage of disease. RT was more immunogenic (81%, 30 out of 37 patients) than integrase and protease (51% and 24%, respectively). CTL recognition of RT was more frequent against Pol amino acids 310-460 (61%, 11 out of 18 patients) than against the other three portions (Pol 168-310, Pol 450-600, Pol 590-728) in patients with CD4 counts > 400 x 10(6)/l, whereas in patients at advanced stages no prominent differences were observed. Two new clusters of antigenic regions were found in the NH2 segment: three epitopes between amino-acids Pol 200 and 217 and four epitopes between amino-acids Pol 346 and 387, using five different HLA-restricting elements. A new cluster of three conserved epitopes was found in the COOH segment of RT.
CONCLUSIONS: This study shows that memory CTL responses against HIV-1 RT, integrase and protease are detectable in most patients at different stages of disease. The capacity of CTL to recognize simultaneously clusters of epitopes may become important for the immune control to reinforce antiretroviral drug efficiency.