A plant-produced influenza subunit vaccine protects ferrets against virus challenge

Background  Influenza A viruses are of major concern for public health, causing worldwide epidemics associated with high morbidity and mortality. Vaccines are critical for protection against influenza, but given the recent emergence of new strains with pandemic potential, and some limitations of the current production systems, there is a need for new approaches for vaccine development. Objective  To demonstrate the immunogenicity and protective efficacy of plant-produced influenza antigens. Method  We engineered, using influenza A/Wyoming/3/03 (H3N2) as a model virus, the stem and globular domains of hemagglutinin (HA) produced in plants as fusions to a carrier protein and used purified antigens with and without adjuvant for ferret immunization. Results  These plant-produced antigens were highly immunogenic and conferred complete protection against infection in the ferret challenge model. The addition of plant-produced neuraminidase was shown to enhance the immune response in ferrets. Conclusions  Plants can be used as a production vehicle for vaccine development against influenza. Domains of HA can generate protective immune responses in ferrets.