S. McAdam

Distinct recognition of closely-related HIV-1 and HIV-2 cytotoxic T-cell epitopes presented by HLA-B*2703 and B*2705.

HIV-1 infection is increasing in many countries where HIV-2 is endemic so the potential interaction between the two strains which differ at the nucleotide level by 40--60% is important. HIV-2 infection is less aggressive than HIV-1 and may protect against HIV-1 infection but this theory is controversial. HIV-specific cytotoxic T lymphocytes (CTL) recognizing conserved viral proteins could mediate cross-immunity. We described extensive cross-reactivity between HIV-1 and HIV-2 CTL epitopes from gag pol and nef presented by HLA-B35. Cross-reactivity was also reported for an HLA-B*2705-restricted HIV-1 epitope; however most CTL epitopes are not cross-reactive (e.g. those presented by HLA-B8 in p17 by HLA-B8 and B14 in gp41 by HLA-CW4 in gp120 and by HLA-B53 in HIV-2 gag). Amino-acid substitutions between HIV-1 and HIV-2 can prevent binding to the HLA molecule or interfere with T-cell receptor (TCR) recognition and may also interfere with recognition of the index sequence. This process of TCR antagonism has been described for naturally occurring variants of HIV-1 hepatitis B virus Epstein--Barr virus and Plasmodium falciparum. (excerpt)