| Two nonhuman primate models of HIV-1 infection were evaluated for their potential utility for vaccine development and testing. First, pigtail macaques were evaluated for their ability to support HIV-1 replication. Although pigtail macaque peripheral blood mononuclear cells (PBMC) supported HIV-1 replication in vitro, there was limited evidence of viral replication in vivo. Two pigtail macaques inoculated with 1 x 10 7 TCID50 of HIV-1LAI developed antibodies to HIV-1 viral proteins but virus was not isolated from these animals at any point. An attempt to achieve a macaque-adapted strain through whole blood transfer was unsuccessful.; A second strategy was to modify molecular clones of SIV by substituting the envelope and other accessory genes from HIV-1. The resulting chimeric viruses, called SHIVs, could be used for the testing of HIV-1 envelope-based vaccines. An unusual strain of SIV, SIVsmmPBj, characterized by marked replication in vivo and rapidly lethal disease, was used as the basis for several SHIV constructs. An SIVsmmPBj-based chimera, SHIV hxb 8, was capable of in vivo replication but not induction of immunodeficiency in pigtail macaques. A second construct, containing a functional HIV-1vpu gene, resulted in a virus which replicated poorly in vitro after transfection but underwent a mutation event which conferred increased replicative ability. This resulting virus replicated somewhat better in vivo than the original SHIV hxb 8. Further attempts to increase pathogenicity through the introduction of biologically relevant HIV-1 patient isolate envelopes resulted in biologically inactive constructs.; The{09}remainder of this work describes the initial development of a novel strategy for an HIV-1 vaccine. Based on the observation that neutralizing antibodies against HIV-1 are rare in natural infection and have been difficult to elicit by vaccination, a novel strategy of passive immunization through gene transfer of preselected antibodies was proposed. A recombinant adeno-associated virus (rAAV) vector for the delivery of a unique broadly neutralizing human antibody, IgGb12, demonstrated transduction in vitro. Scid mice inoculated intramuscularly with 1 x 1011 DNase resistant particles (DRP) rAAV/CMV/IgGb12 developed levels of circulating human IgG1 up to 1300 ng/ml. Rhesus macaques inoculated with 2.6 x 1112 and 6 x 1012 DRP did not develop detectable levels of IgGb12. |
