AEGiS-14IAC: SIV Gag-expressing recombinant BCG-prime and recombinant vaccinia virus DIs strain-boost regimen evokes protective immune response in monkey.

14th International AIDS Conference

Barcelona, Spain - July 7-12, 2002

SIV Gag-expressing recombinant BCG-prime and recombinant vaccinia virus DIs strain-boost regimen evokes protective immune response in monkey.

Int Conf AIDS 2002 Jul 7-12; 14:(abstract no. TuOrA1222)

Matsuo K, Nakasone T, Izumi Y, Ami Y, Ohsu T, Hamano T, Yamamoto N, Yamazaki S, Honda M
JST AIDS Vaccine Project, c/o National Institute of Health, Ministry of Public Health, Nonthaburi, Thailand

BACKGROUND: To develop Gag antigen-targeted recombinant vector-based AIDS vaccine, we constructed a whole SIV Gag antigen-expressing recombinant live vector vaccines using Mycobacterium bovis BCG (BCG) and highly attenuated vaccinia virus DIs strain which is nonreplicative in human. Protective efficacy was evaluated for prime and boost regimen using these two recombinant vectors in cynomolgus monkey.

METHODS: Gag gene from SIVmac 239 was PCR-amplified, introduced into hsp60 promoter-based BCG expression vector and then transformed into BCG Tokyo substrain. On the other hand, the same gag gene was cloned to a transfer vector for vaccinia virus DIs strain by inserting the gene downstream of p7.5 promoter. The vector was introduced into virus genome by homologous recombination. Gag gene expression was confirmed by immunoblot assay for lysates of recombinant BCG (rBCG) and recombinant vaccinia virus DIs (rDIs)-infected chick embryo fibroblast cell by using anti-Gag monoclonal antibody. Gag-specific lymphocyte proliferation, gamma-IFN ELISPOT and intracellular cytokine staining assays were carried out for peripheral blood mononuclear cell of immunized monkey after stimulation with Gag p27 protein. After SHIV rectal challenge (2000TCID50), CD4 positive cell number and plasma viral load were monitored periodically.

RESULTS: We have successfully established rBCG-SIVgag and rDIs-SIVgag clones both of which remarkably express SIV Gag antigen. rBCG-SIVgag-primed (10 mg, sc) and rDIs-SIVgag-boosted (108 pfu, iv) monkeys showed drastically stronger cellular immune responses than in monkeys immunized with each vector alone. These monkeys were partially protected from pathogenic SHIV-C2/1 challenge. Set points of plasma viral load were suppressed at least 100-times lower than in naïve monkeys.

CONCLUSION: The prime and boost regimen using rBCG and rDIs systems may provide novel safe and effective candidate AIDS vaccines.

Keywords: AEGIS, SIV, Vaccinia virus, Mycobacterium bovis, Gene Products, gag, Vaccines, Synthetic, AIDS Vaccines, Genes, gag, Genetic Vectors, Macaca fascicularis, CD4-Positive T-Lymphocytes, Viral Load, Tokyo, Animal, Human, immunology, genetics

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TuOrA1222