الفهرس 
Experimental plan 1 assessment of inactivated NDV genotype II, inactivated rNDV genotype VII, and inactivated autogenous vNDV genotype VII effectiveness against challenge with vNDV genotype VII.I.I (AccessionNo.:MG029120) challenge in commercial broiler chickens at 28 days of age.Only 14 pages are availabe for public view
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Abstract
Newcastle disease virus is a serious threat to the poultry industry worldwide, Genotype VII Newcastle disease viruses (NDV) are still circulating in Egypt despite intensive vaccination programs. In this study we evaluate some vaccination regimes against Genotype VII 1.1 Newcastle disease viruse challenge in commercial broiler. In 1st experiment, 3 groups of birds (G1-3) received 3 different vaccine regimes involving geno-type II NDV, recombinant genotype VII NDV-matched, and an autogenous velogenic NDV genotype VII vaccine that were evaluated against challenge with velogenic NDV genotype VII 1.1. Three vaccination regimes were applied as follows: G-1 received inactivated genotype II, G-2 received inactivated recombinant genotype VII NDV-matched, and G-3 received velogenic inactivated autogenous NDV genotype VII vaccines given at the age of 7 day while the live vaccine doses, each group received the same live genotype II vaccine, Groups (G1-3) were challenged with NDV genotype VII applied on day 28. Evaluation of protection after challange based on clinical signs, gross lesions, mortality rate, seroconversion, virus shedding, and microscopic changes. The results showed that these three vaccination regimes partially protected commercial broilers (77%, 86%, 97%, respectively, vs. 9 % in non-vaccinated challenged against mortality. The result of virus shedding and microscopic changes in all vaccinated groups (G1-3) significantely reduced compared to the non-vaccinated group (G-4). In the 2nd experiment we evaluate the protective efficacy of (rHVT-ND) vector vaccine against challenge with velogenic NDV genotype VII 1.1 at 28 day of age. Five vaccination regimes were used; G1 vaccinated only with rHVT-ND vaccine, G2 vaccinated by HVT-ND and 2 live ND vaccines, G3 vaccinated by rHVT-ND, inactivated ND and 2 live ND vaccines, G4 vaccinated by 2 live ND vaccines, G5 vaccinated by inactivated ND and 2 live ND vaccines, G6 non-vaccinated challenged and G7 non-vaccinated non-challenged . The protection conferred by all vaccines regimes was evaluated after experimental infection based on mortality rate, clinical signs, gross lesions, seroconversion, detection of HVT virus in the spleen, virus shedding and microscopic changes. The results showed that the protection rates were 76.7 %, 86.7%, 66.7% and 96.7%, respectively, in G1, G2, G4 and G5while the best protection was 100% in G3 vs 10 % in G6.. The result of MLS and virus shedding at the level of the number of shedders and the amount of virus shedding in all vaccinated groups significantly reduced compared to the non-vaccinated challenged group (G-6) while G3 and G5 also show the more reduction of virus shedding and microscopic changes. In conclusion, using closely genotype-matched vaccines (NDV- GVII) provided higher protection than using vaccines that were not closely genotype-matched and non-genotype-matched and the complete clinical protection against challenge with genotype VII.I.I NDV was revealed in commercial broiler chickens vaccinated with HVT-ND, inactivated ND and 2 live ND vaccines (G3). As a regimes recommended to be used in endemic countries