HGP-30 is an artificially manufactured copy of the p17 protein made by genetic engineering techniques. p17 is a core protein of HIV, which does not mutate to the same extent that the virus's envelope does. In people with HIV, antibodies to p17 usually appear soon after infection but gradually disappear as the disease progresses. One theory is that those antibodies help protect against HIV's harmful effects.

HGP-30 is based on the hypothesis that by injecting this protein into people who are already infected with HIV, the immune system may be stimulated to produce higher levels of anti-p17 antibodies as well as cellular responses against not only HGP-30 but also the `real' protein found in HIV particles. HGP-30 is also being investigated as a preventive vaccine to protect uninfected people.

HGP-30 is being developed by CEL-SCI Corporation.

Current use

Phase I studies of HGP-30 in 38 healthy HIV-negative volunteers in London, San Francisco and Los Angeles suggested that the vaccine is well-tolerated and induces antibodies and cytotoxic T-cells. Further Phase I studies in HIV-positive and HIV-negative volunteers began in the USA in early 1995, and in 1997 Cel-Sci reported strong lymphocyte responses to p17 in HIV-positive individuals vaccinated with HGP-30. However, no data from this study has been published and future development plans for HGP-30 as an immunotherapy or preventive vaccine are unknown.

Key research

HGP-30 is a recombinantly produced portion of the p17 gag core protein of HIV-1. It is coupled with a keyhole limpet haemocyanin (KLH) carrier and an alum adjuvant. HGP-30 is being studied as an HIV vaccine for non-infected people and as immunotherapy in HIV-positive asymptomatic people.

Achour observed that in vitro when immortalised B-cell lines from HIV-positive individuals were pulsed with HGP-30, HIV-specific CTLs were generated in autologous mixed lymphocyte culture.

Sarin reported that three phase I studies in which 38 HIV-negative male volunteers were injected intramuscularly with escalating doses of HGP-30. The vaccine induced cytotoxic T-cell (11/25) and lymphocyte proliferation responses to HGP-30/p17 (24/29) as well as antibody responses to HGP-30 (29/38). CTL responses were observed in a higher number of individuals (9/18) at the lower dose levels (10 and 25 µg/kg) than those (2/7) at higher doses (50 or 100 µg/kg).

Willer studied the response of HIV-positive individuals infected with HIV to HGP-30 at various stages of disease progression. A PBMC proliferative response to HGP-30 was seen in 40% of the healthy seroconverted patients, in 35% of the CDC stage III patients and in 18% of the CDC stage IV patients. There was no correlation between the proliferative response to HGP-30 and other antigens or to CD4 cell count.

References

Achour A et al. HGP-30, a synthetic analogue of human immunodeficiency virus p17, is a target for cytotoxic lymphocytes in HIV-infected individuals. PNAS 87(18):7045-7049, 1990.

Sarin PS et al. HIV-1 p17 synthetic peptide vaccine HGP-30: induction of immune response in human subjects and preliminary evidence of protection against HIV challenge in SCID mice. Cellular and Molecular Biology 41(3):401-407, 1995.

Willer A et al. Cell-mediated immunity against HGP-30, a group-specific peptide of HIV p17 in individuals infected with the AIDS virus. Biomed Pharmacother 46(8):359-365, 1992.