High immune efficacy against different avian influenza H5N1 viruses by oral administration of a Saccharomyces cerevisiae-based vaccine in chickens

Abstract

BackgroundA safe and effective vaccine is the best way to control large-scale highly pathogenic avian influenza virus (HPAI) A (H5N1) outbreaks. Saccharomyces cerevisiae (S. cerevisiae) is an ideal mucosal delivery vector for vaccine development, and we have previously shown that conventional injection administration with a S. cerevisiae-based vaccine (EBY100/pYD1-HA) was protective against homologous H5N1 virus in a mouse model. Due to the diameter of S. cerevisiae is around 10 μm which results in a severe inflammation by injection route, therefore, oral administration is a more suitable approach for EBY100/pYD1-HA conferring cross-protection in poultry. ResultsWe extended our work by evaluating the immunogenicity and cross-protective efficacy of oral vaccination with EBY100/pYD1-HA in the chicken model. Oral immunization with EBY100/pYD1-HA could induce robust serum IgG, mucosal IgA and cellular immune responses. Importantly, EBY100/pYD1-HA provided complete cross-protection against different H5N1 viruses challenge. ConclusionsThese findings suggest EBY100/pYD1-HA, a promising H5N1 oral vaccine candidate, can avoid potential reassortment of other avian influenza viruses in oral administration of live virus vaccines and overcome the drawbacks of conventional injection route. Importantly, this platform will be able to provide opportunities for broader applications in poultry during HPAI A (H5N1) outbreaks.