Comparative evaluation of the immune responses of seven chicken ecotypes to vaccination against Newcastle disease

Abstract

Newcastle disease (ND) is a highly contagious viral disease of poultry with high mortality. The local velogenic viral pool of the ND strains influences its severity and occurrence. ND vaccination is the most feasible approach to control the disease. However, some ND-vaccinated groups within chicken populations are susceptible to velogenic ND infection developing outbreaks with marked pathological lesions and shedding of the virus. Vaccine strain-related factors as well as inadequate vaccine application and delivery methods during vaccination might explain the suboptimum ND vaccine efficacy. In this study, however, we propose that host factors may contribute to the suboptimal vaccine efficacy in vaccinated chickens. We, therefore, compared the immune response of five Ethiopian chicken ecotypes to ND immunization in the presence of two reference breeds (Fayoumi and Bovans). All chickens received initial immunization at age of 21 days with HB1 ND vaccine followed by two-times LaSota booster immunization at age 50 and 120 days. Subsequently, serum was collected fortnightly post-vaccination at age 35, 65, and 135 days for immune response analysis using the hemagglutination inhibition (HI) test. HIantibody was significantly higher at days 135 > 65 > 35 in each ecotype following the third, second, and first vaccination, respectively. The different chicken ecotypes had significant differences in HI antibody response to the ND vaccination. Accordingly, the HI titer was significantly higher in Jarso > Cheffe > Fayoumi > Arsi > Bovans > Tepi > Horro suggesting antibody titer and ND vaccine efficacy of the ND vaccine depends on host factors. Moreover, some chicken groups within each ecotype had low HI titer. Chicken ecotypes with weak immune responses may not completely clear the virus from their body; thus, they can serve as a reservoir host by maintaining the ND virus. We conclude that herd immunity level and blanket vaccination program based on the results of a single host genetic group can be misleading during developing and recommending a new vaccine. Hence, understanding the host determinant factors in the immune response during vaccination can lead to improved efficacy and protection against ND in chicken populations.

Evaluation of the immune response of layer chickens to Newcastle disease virus vaccines using the new vaccination regimens

“…(2020). Administering a double dose of vaccination to a flock of chickens addresses the variability in immune responses, ensuring that even birds with weaker immune systems can develop protective immunity (Nedeljkovic et al., 2022; Illango et al., 2005; Sarba et al., 2021). This finding also supports previous study (Hu et al., 2022; Dimitrov et al., 2017; Miller et al., 2013; Ravikumar et al., 2022), which found that a double dose offers a higher concentration of antigens, boosting the possibility of a stronger and more effective immune response in chickens.…”

Probiotics in Industrial Poultry Farming

“…By incorporating recombinant Lactobacillus cultures in poultry diets, broilers have gained significantly in weight, resulting in lower production costs and reduced environmental impact (Rinttilä and Apajalahti, 2013;Lantseva et al, 2015;Temiraev et al, 2016;Lin et al, 2022). Not only can probiotics reduce nutrient requirements by increasing nitrogen and phosphorus utilization, but some probiotics have also demonstrated significant immunomodulatory potential (Eeckhaut et al, 2016;Bilal et al, 2021;Khodorovich, 2021;Sarba et al, 2021). Protection against pathogens and facilitation of digestion and nutrient utilization can be addressed by modulating the immune response (Askelson et al, 2014;Gong et al, 2018;He et al, 2019).…”