Assessment of Immunological Responses of Broilers Vaccinated with Newcastle Strains Using Either Spray or Water Delivery Systems

ABSTRACT (1) Background: Vaccine programs have been failing to provide complete immunity against the Newcastle disease virus (NDV). This study examines the immunological responses to the live LaSota and Avinew (VG/GA) vaccines given through spray or drinking water to broiler chickens; (2) Methods: The experimental vaccination included one unvaccinated control group and four other groups of the same size. There were three duplicates, each with 30 birds, with each group amounting to ninety birds. In addition to the status of the cellular and humoral immunity, we examined the weights and histology of the bursa and spleen; (3) Results: The bursa weight index (BWI) significantly increased on days 28 and 42 in the vaccinated groups, regardless of the vaccination method (p≤0.05). The spleen weight index (SWI) significantly increased on day 42 in VG/GA vaccinated birds, and on day 28 in chicks vaccinated with the LaSota strain (p≤0.05). T cell proliferation in response to stimulation with PHA was significantly higher across all vaccinated groups compared to the unvaccinated ones. Serum IgG was significantly elevated on days 21, 28, and 42 post-vaccination with VG/GA or LaSota strain for both vaccination routes (p≤0.05); (4) Conclusions: The data generated from this study demonstrated that significant immune responses can be generated with the two examined Newcastle vaccine strains using the spray and drinking water vaccination routes.