AN HIV TYPE-2 DNA VACCINE INDUCES CROSS-REACTIVE IMMUNE-RESPONSES AGAINST HIV TYPE-2 AND SIV

We have previously reported on the generation of specific functional i mmune responses after inoculation of animals with expression vectors e ncoding HIV-1 genes. This article provides the details of the first ap plication of this new technology to induce immune responses against HI V-2. This virus is molecularly and serologically distinct from HIV-1 a nd is in fact more closely related to the simian immunodeficiency viru s (SIV). Anti-HIV-2 and SIV antibodies were induced in mice of three d ifferent haplotypes following a single intramuscular inoculation with an HIV-2/ROD envelope glycoprotein expression vector (pcEnv-2). Boosti ng of animals with pcEnv-2 induced both anti-HIV-2 neutralizing antibo dies and T cell-proliferative responses against HIV-2 and SIVmac prote ins. We compared the humoral and cellular immune responses of mice inj ected with pcEnv-2 and then boosted with either the homologous DNA con struct or a recombinant Env protein. Animals boosted with pcEnv-2 gene rated B and T cell immune responses as strong as those of mice boosted with recombinant gp140 protein in adjuvant. Finally, cellular immune responses were significantly increased with the coadministration of pc Env-2 and a plasmid expressing interleukin 12, We therefore conclude t hat DNA plasmid inoculation induces cross-reactive anti-HIV-a and anti -SIVmac immune responses in mice, This technology should be further in vestigated as a potential vaccine component for this human pathogen.