Evaluation of influenza virus-like particles and Novasome adjuvant as candidate vaccine for avian influenza.

The development of safe and effective vaccines for avian influenza viruses is a priority for pandemic preparedness. Adjuvants improve the efficacy of vaccines and may allow antigen sparing during a pandemic. We have previously shown that influenza virus-like particles (VLPs) comprised of HA, NA, and M1 proteins represent a candidate vaccine for avian influenza H9N2 virus [Pushko P, Tumpey TM, Fang Bu, Knell J, Robinson R, Smith G. Influenza virus-like particles comprised of the HA, NA, and M1 proteins of H9N2 influenza virus induce protective immune responses in BALB/c mice. Vaccine 2005;23(50):5751-9]. In this study, an H9N2 VLP vaccine and recombinant HA (rH9) vaccine were evaluated in three animal models. The H9N2 VLP vaccine protected mice and ferrets from challenge with A/Hong Kong/1073/99 (H9N2) virus. Novasome adjuvant improved immunogenicity and protection. Positive effect of the adjuvant was also detected using the rH9 vaccine. The results have implications for the development of safe and effective vaccines for avian influenza viruses with pandemic potential.