Experimental Efficacy Evaluation of Different Vaccination Programs for Epidemic Newcastle Disease Virus in Egypt Against Challenge with Velogenic Genotype VII 1.1 in Commercial Broiler Chickens
Experimental Efficacy Evaluation of Different Vaccination Programs for Epidemic Newcastle Disease Virus in Egypt Against Challenge with Velogenic Genotype VII 1.1 in Commercial Broiler Chickens
Hagar Magdy Ahmed1, Mohamed Mahrous Amer2*, Khaled Mohamed Elbayoumi1 , Sameh Abdel- Moez Ahmed Amer1, Asmaa Mahmoud Matoaq1 , Mohamed Abdel Aziz Kutkat1, Gomaa Abd El-Rhim Abdel-Alim2
ABSTRACT
Different Newcastle disease virus (NDV) vaccines and programs are heavily applied in poultry farms, but there is no marked protection against NDV genotype VII. So, the need of improved vaccines and vaccination protocols to reduce clinical disease and mortality is necessary. The current study evaluated the efficacy of different NDV vaccines used in poultry flocks in Egypt: live attenuated NDV vaccines (genotype II) and live recombinant herpes virus of turkey (rHVT-ND-IBD) alone or in combination with inactivated NDV vaccines either of genotypes II or VII (commercially available or autogenously prepared). Different vaccination regimes are applied at various designated days to 260 commercial broiler chickens in 13 groups; 20 birds each. At 28 days-old, all groups were challenged with NDV genotype VII 1.1 strain “NDV-CHICKEN-EGY-ALEX-NRC-2020” to evaluate the protective immunity of applied protocols. Humoral immune response, clinical signs, post-mortem gross lesions, growth performance as well as mortalities are all recorded and evaluated. All vaccination protocols were able to induce antibody levels for NDV after vaccination with varying titers. Overall, the serological response at challenge day were significantly with higher titers in groups vaccinated with inactivated NDV genotype VII vaccines when compared with other groups. Regarding broiler performance parameters it was noticed that, there is no significant difference in body weight (BW) as well as feed conversion rate (FCR) among all chickens in different vaccinated groups. From these findings, we concluded that vaccination programs include ND vaccines genotypically- matched to challenge virus in combination with live attenuated NDV vaccines provided a significant protection against mortality and clinical disease when compared with conventional vaccination regimes.
Keywords | Newcastle disease virus; Vaccination protocols; Growth Performance; Protective immunity; Genotype-matched vaccines.
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