The key experimental observations that form the basis for the proposed studies are that alphavirus RNA replicon vectors, when appropriately configured and delivered in virus-like replicon particles (VRP) can function as highly potent adjuvants for co-administered protein immunogens, including influenza HA. When inoculated into animals, these replicon-based adjuvants promote significant T cell responses to HA proteins which are not observed when the protein is inoculated alone, and can enhance HA-specific antibody responses by 10-50 fold depending on the dose of HA protein inoculated. In addition, a single inoculation of the combined VRP adjuvant and HA protein typically induces higher antibody responses than observed with two doses of the protein alone given at the same dose. Thus, these replicon-based adjuvants show significant potential as dose-sparing and immune-enhancing adjuvants for influenza, and may allow a single inoculation vaccination in circumstances currently requiring two inoculations (pediatric population and pandemic setting). Two such VRP adjuvant approaches have been identified in rodent studies using alphavirus replicon vectors and co-administered recombinant HA protein. In the first approach, the VRP vectors express the cytokine, IL-12, and in the second approach, the replicon vectors express the same HA protein with which it is formulated in the combined vaccine. The first adjuvant approach is therefore a generic strategy, whereas the second approach would require individual HA VRP products for each influenza strain included in the vaccine. Both approaches are significantly more potent than """"""""null"""""""" VRP, i.e. VRP that do not express a transgene. The objectives of the proposed research are to extend these adjuvant strategies to traditional, split-product influenza vaccines and optimize their performance for these available products, to extend the existing studies to nonhuman primates, and to carry out process development that would be sufficient to allow a transition to GMP production.
