DNA vaccines engineered to elicit immune responses against HIV-1 can induce humoral and cellular immune responses in a variety of species. We have reported on the development of a multi-cassette system for the production of broad-based immune responses in vivo against the majority of HIV-1 open reading frame encoded antigens. Our group has shown that through a multiple immunization regime this approach can impact on viral load in primate models of infection. Specifically, we have shown that DNA vaccine constructs can protect chimpanzees from HIV challenge, can protect a subset of macaques from SHIV challenge as well as appear to function as therapeutic agents to lower viral load in infected chimpanzees. Preliminary studies demonstrate that HIV-1 DNA vaccines are apparently well tolerated and are immunogenic in humans (see Administrative core and overview, Project 3 and Immunology Core). However, it is unclear the degree to which the type of immunity induced will be capable of impacting on HIV infection in a natural setting using these first generation vaccines. Furthermore the multiple immunization scheme we used previously in the chimpanzee model might be cumbersome for testing of these vaccine candidates. In this regard, it may be important to specifically engineer immune responses in order to improve on first generation vaccine attempts. Especially for HIV, induction of cell-mediated immunity may be an important feature for any candidate vaccine as such responses could interrupt the establishment of infection. The humoral infection response may play a role in limiting viral entry and slowing viral spread during the infection process. Furthermore the induction of chemokines in such immunization procedures may be important for limiting viral entry and infection (see Project 2). This project will attempt to engineer enhancement of in vivo cellular and humoral immune responses to HIV-1 DNA vaccine cassettes through the use of immunomodulatory gene constructs. A panel of immunomodulatory genes will be studied in a system which we have designed and exploited Studies will be performed in mice, and both macaques and chimpanzees to characterize and optimize immunogenicity of these novel constructs. The effects of these vaccine candidates to impact viral load in challenge studies will be monitored. These studies will allow us to develop a new generation of HIV-DNA vaccine for testing in humans (see Project 3). Additionally, these studies are designed to enhance our understanding of the types of immune responses which are correlated with any observed protection by not just observing and cataloguing induced responses but on the front end driving responses in a particular immunological direction.

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