Engineered Newcastle disease virus expressing the haemagglutinin protein of H9N2 confers protection against challenge infections in chickens

Abstract

The Newcastle disease (ND) and avian influenza (AI) are two crucial viral ailments of poultry birds. In field conditions, these are controlled by vaccination and biosecurity measures. The cumbersome application process, potential for reversion to the wild pathogen, and financial load on farmers are only a few drawbacks of the currently available ND and AI vaccines. There was a pressing need to develop a stable, safer, bivalent vaccine for these two diseases. Hence, this study adopts the reverse genetic technology, thereby rescuing the recombinant LaSota strain of NDV, which expresses the haemagglutinin (HA) protein of indigenously isolated H9N2 virus (rNDV-H9). The rNDV-H9 was tested in terms of pathogenicity and growth kinetics. Subsequently, the day-old broiler chicks were immunised with rNDV-H9, followed by challenge infection by virulent NDV and H9N2 viruses. The results indicate that immunisation with rNDV-H9 has reduced the shedding of challenge viruses. The clinical progression of the diseases was slowed down, and all the birds were seroconverted. Results in this study indicate that rNDV-H9 is a promising candidate for immunisation in endemic areas of ND and AI, with minimum economic pressure on farmers and reduced vaccinal stress on poultry birds.