Influenza virus-like particle vaccines.

Enveloped virus-like particle (VLP) vaccines containing influenza hemagglutinin (HA) and neuraminidase (NA) antigens are produced easily in insect or mammalian cells via the simultaneous expression of HA and NA along with a viral core protein, such as influenza matrix (M1) or a retroviral Gag protein. The size and shape of the resulting particles are dictated by the choice of the core component, but M1- and Gag-based VLPs are strongly immunogenic and protective in seasonal and highly pathogenic influenza challenge models. Current data are consistent with the hypothesis that influenza VLP vaccine efficacy is related to the particulate, multivalent composition coupled with the presence of correctly folded antigens with intact biological activities. This new influenza vaccine paradigm offers potential advantages over the conventional egg-based, split-vaccine platform in terms of enhanced immunogenicity and better breadth of protection.