AEGiS-14IAC: Development of an HIV-1 subtype C DNA candidate vaccine targeted for South Africa.

14th International AIDS Conference

Barcelona, Spain - July 7-12, 2002

Development of an HIV-1 subtype C DNA candidate vaccine targeted for South Africa.

Int Conf AIDS 2002 Jul 7-12; 14:(abstract no. TuOrA1223)

Williamson C, van Harmelen JH, Shephard E, Londt B, Gray C, Morris L, Karim SA, Swanstrom R, Williamson AL
University of Cape Town, Cape Town, South Africa

BACKGROUND: This project forms part of a national initiative to develop HIV-1 vaccines for use in South Africa under the support of the South African AIDS Vaccine Initiative. As part of a prime-boost strategy, we report on the identification of genes for inclusion into vaccines and the construction of a DNA vaccine expressing subtype C gag.

METHODS: HIV-1 gag, pol, env, nef and tat genes were analysed for inclusion into vaccines. The gag gene was resynthesized to reflect the codon usage of highly expressed human genes and cloned into pTH DNA vaccine vector (pTHgagC). Expression was assessed by immunfluorescence and western blot. Immunogenicity in BALB/c mice was determined by chromium release cytotoxic T cell (CTL) assays and intra-cellular cytokine (ICC) assays.

RESULTS: Sequence analysis identified subtype C as the predominant HIV subtype at targeted vaccine trial sites. South African amino acid consensus sequences were generated from recently infected individuals and gag, pol, env, nef and tat genes were selected based on closest relationship to the consensus sequences. Immunoflourescence and western blot analysis confirmed expression of the Gag protein from pTHgagC. A single intramuscular inoculation of the 100 ug DNA vaccine elicited a vigorous antigen specific CTL response in BALB/c mice. In addition, ICC assays demonstrated that 10 days after immunization, 27 % of CD8+ T-cells produced IFN-γ in response to a Gag peptide, compared to 15% of CD8+ T-cells 49 days post immunization, indicating that memory is maintained.

CONCLUSION: Multiple genes have been characterised for inclusion into vaccines. To date the gag gene has been resythesized, inserted into the DNA vaccine vector and shown to induce a cell mediated immune response. Our goal is to develop DNA vaccines expressing multiple HIV genes as part of a DNA prime / MVA boost approach.

Keywords: AEGIS, AIDS Vaccines, Genes, gag, Gene Products, gag, HIV-1, Vaccines, DNA, HIV Infections, Genes, tat, HIV, HIV Antibodies, Immunization, T-Lymphocytes, Cytotoxic, Antigens, CD8, T-Lymphocytes, Vaccination, South Africa, Human, Animal, Mice, growth & development, genetics, immunology

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TuOrA1223