نوع مقاله : مقاله پژوهشی
عنوان مقاله English
نویسندگان English
Objective
Newcastle disease (ND) is still one of the major viral diseases that affects the broiler production industry and has significant negative effects on flock-level health, mortality, and productivity. The aim of the present study was to compare four Newcastle vaccination schedules in Ross 308 broiler chickens to assess and compare between groups the expression of immune-related genes, pre- and post-challenge antibody responses, and protection against challenge with an acute field isolate of Newcastle virus.
Materials and methods
Five experimental groups were randomly created with each group consisting of 50 one-day-old Ross 308 broilers. Group 1 (G1) was vaccinated on day one with a commercial killed genotype VII Newcastle disease vaccine. Group 2 (G2) received VACCINDO (Flu H9N2 + ND) and Group 3 (G3) received CAVAC (Flu H9N2 + ND). Group 4 (G4) was vaccinated using a commercial live vaccine of the La Sota strain of Newcastle disease. Group 5 (G5), the control, did not receive any vaccinations. The humoral immune response of each group was determined using ELISA on days 1, 10, 23 and 30 post-hatching. Real-time PCR was used to evaluate the expression of the immune-related genes encoding interleukin-1 beta (IL-1β) and interferon-gamma (IFN-γ). All birds were challenged orally with a virulent isolate of Newcastle disease virus (PQ800135.1) at 23 days of age.
Results
The results showed that all groups had equal baseline maternal antibody titers at one day of age. At 23 days of age, immediately before challenge, G1 showed the highest ND antibody titer among all vaccinated groups, indicating the strongest pre-challenge humoral immune status. G1 also recorded the highest expression of both IL-1β and IFN-γ, suggesting superior activation of innate inflammatory and IFN-γ-associated antiviral immune responses. Following challenge, the lowest mortality rate was observed in G1 (10%), compared with 22%, 24%, 30%, and 90% in G2, G3, G4, and G5, respectively.
Conclusion
The results of the trial showed that the most favorable overall profile of pre-challenge antibody response, immune gene expression, and survival after acute NDV challenge was achieved by the commercial inactivated genotype VII ND vaccine in G1. Therefore, it can be concluded that this vaccination program, compared to the other programs evaluated, can provide better protection.
کلیدواژهها English