Recombinant-attenuated Salmonella pullorum strain expressing the hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) protects chickens against NDV and Salmonella Pullorum challenge.

Newcastle disease virus (NDV) and Salmonella Pullorum (S. Pullorum) have great damage to the poultry industry, but no perfect vaccine can protect them effectively until now. In this study, a recombinant-attenuated S. Pullorum strain secreting Newcastle disease virus hemagglutinin-neuraminidase (HN) protein, C79-13ΔcrpΔasd (pYA-HN), was constructed as a new bivalent vaccine candidate against Newcastle disease and S. Pullorum disease (PD) by the method of suicide plasmid pREasd-mediated bacteria homologous recombination. The effect of this vaccine candidate was compared with NDV LaSota strain and C79-13ΔcrpΔasd (pYA) strain. The serum HI antibody titers, serum IgG antibodies, the intestinal sIgA and stimulation index in lymphocyte proliferation were significantly higher (P<0.01) induced and increased in chickens inoculated with C79-13ΔcrpΔasd (pYA-HN) strains compared with that of the C79-13ΔcrpΔasd (pYA) strain and were not significantly increased compared with that in the chicken immunized with LaSota live vaccine (P>0.05). And it could provide 60% and 80% protective efficacy against NDV virulent strain F48E9 and S. Pullorum virulent strain C79-13. In summary, the results indicate that recombinant-attenuated S. Pullorum (SP) strain secreting NDV HN protein was constructed, and the generation of C79-13ΔcrpΔasd (pYA-HN) strain provides a good foundation for the development of an effective living-vector double vaccine against NDV and S. Pullorum.