Newcastle disease virus (NDV) recombinant expressing the hemagglutinin of H7N9 avian influenza virus protects chickens against NDV and highly pathogenic avian influenza A (H7N9) virus challenges.

The emerged highly pathogenic avian influenza A (H7N9) (HPAI) viruses in China pose a dual challenge to public health and poultry industry. Thus H7N9 vaccines are in an urgent need. In this study, we constructed a Newcastle disease virus (NDV)-vectored vaccine (rLXHAF) expressing the hemagglutinin (HA) of H7N9 virus fused with the transmembrane/cytoplasmic tail domain of the NDV fusion protein. rLXHAF stably expressed the HA protein, exhibited similar growth kinetics and pathogenicity as the parental virus. rLXHAF induced positive NDV-specific hemagglutination inhibition (HI), virus neutralization (VN) and total IgY antibodies and completely protected chickens from NDV challenge. Unexpectedly, rLXHAF elicited undetectable HI and VN titers but high overall IgY antibody titers against H7N9 measured by ELISA. The vaccine provided 80% protection against HPAI H7N9 challenge. Virus shedding of NDV and H7N9 challenge strains was reduced. Our results suggest that rLXHAF is immunogenic and efficacious against HPAI H7N9 virus in chickens.