Cytotoxic and humoral immune responses to HIV-1 p17 synthetic peptide HGP-30 in human volunteers

A 30-amino acid synthetic HIV-1 p17 peptide, HGP-30, linked to KLH with alum as the adjuvant was evaluated as a candidate HIV-1 vaccine in 38 HIV-1-seronegative volunteers in 2 separate clinical trials in London and California. The vaccine was well tolerated and most immunized volunteers showed antibody responses to HGP-30 (29 of 38) and KLH (38 of 38). Cytotoxic T cell (CTL) (11 of 25) and T cell proliferation responses to KLH (20 of 20) and HGP-30/p17 (24 of 29) were observed in cells from immunized volunteers. The CTL response has been shown to be CD8⁺. A higher proportion of vaccinees (10 of 18) in the lower-dose groups (10 and 25 μg/kg) showed CTL activity than the vaccinees (1 of 7) in the higher-dose groups (50 and 100 μg/kg). These results suggest that lower vaccine doses may be important in inducing T(H)-1 cell responses necessary for protective cell mediated immunity. Pilot studies in SCID mice reconstituted with cells from an HGP-30-vaccinated volunteer showed protection in 75% of mice against HIV-1 challenge with a 10,000 TCID₅₀ dose of live virus. These studies suggest that HGP-30 is an important epitope for induction of humoral and protective cell-mediated immune responses.