Broadened immunity and protective responses with emulsion-adjuvanted H5 COBRA-VLP vaccines.

A number of challenges for developing a protective pre-pandemic influenza A vaccine exists including predicting the target influenza strain and designing the vaccine for an immunologically naïve population. Manufacturing and supply of the vaccine would also require implementing ways to increase coverage for the largest number of people through dose-sparing methods, while not compromising the potency of the vaccine. Previously, our group described a novel hemagglutinin (HA) for H5N1 influenza derived from a methodology termed computationally optimized broadly reactive antigen (COBRA). This report describes a strategy combining a COBRA-based HA vaccine with an oil-in-water emulsion, resulting in a dose-sparing, immunologically broadened, and protective response against multiple H5N1 isolates. Here, we show that an emulsion-based adjuvant enhances the magnitude and breadth of antibody responses with both a wild-type H5HA (H5N1 WT) and the H5N1 COBRA HA VLP vaccines. The H5N1 COBRA HA VLP, combined with an emulsion adjuvant, elicited HAI specific antibodies against a larger panel of H5N1 viruses that resulted in protection against challenge as efficiently as the homologous, matched vaccine.