[MoOrA1088] Development and evaluation of novel forms of DNA vaccines against HIV-1

14th International AIDS Conference

Barcelona, Spain — July 7-12, 2002

[TITLE:] Development and evaluation of novel forms of DNA vaccines against HIV-1

[AUTHOR(S):]B.K. Felber, G. N. Pavlakis, M. Rosati, P. Eyler, A. Valentin, H. Trivedi, A. Biragyn, L.W. Kwak, A. von Gegerfelt¹, P. Markham, R. Woodward², N. Miller³

Int Conf AIDS. 2002 Jul 7-12;14:Abstract No. MoOrA1088

BACKGROUND: DNA-based immunogens promise to provide simple and cost-effective vaccines, although their potential has not been fully explored.

METHODS: We have generated several vectors that express HIV or SIV structural proteins independently of the normal HIV-encoded regulatory system (Rev/RRE).The expression vectors eliminated the inhibitory sequences from the coding regions.A second generation of vectors was also produced, in which the N-termini of the viral proteins were fused either to a secreted protein (MCP-3 chemokine), or to a peptide containing the beta-catenin ubiquitinization signal.Analysis showed that MCP-3 targeted the viral proteins to the secretory pathway; whereas the beta-catenin peptide which targeted the viral proteins to the proteasomal degradation pathway.

RESULTS: Expression and immunogenicity of secreted and intracellular forms of antigens were compared to the native forms.We found that a combination of different forms of antigens resulted in improved immunogenicity. Fusions of gag to MCP-3 chemokine stimulated more efficient humoral responses.Antibody titers of up to 1:12800 were measured in immunized macaques.Interestingly, macaques immunized with combinations of three forms of antigens showed the broadest immune responses, since 3/4 animals developed high titer antibodies and all had strong cellular immunity as determined by proliferation and intracellular cytokine measurements.

CONCLUSIONS: Preliminary data after 4 vaccinations indicate that all animals have measurable specific immune responses.The results in macaques agree with the mouse experiments, in that the behavior and rank of DNA vectors compared to each other is similar.This allows the use of mouse vaccination as a rapid tool for further improvement of vaccine candidates.These data demonstrate the development of a more balanced immune response than previously anticipated by DNA vaccination in macaques, using the new generation of DNA vectors.

Presenting author: Pavlakis, George

1NCI-Frederick, National Cancer Institute at Frederick, 1050 Boyles Street, Bldg. 535, Rm. 206, Frederick, Maryland 21702-1201, United States.

2Advanced BioScience Laboratories, Inc., Kensington, United States.

3NIAID, Bethesda, United States.

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