الفهرس 
cover englishOnly 14 pages are availabe for public view
 |  | from | 174 |  |  |
| | | from | 174 | | |
Abstract
Eighty five chicken flocks (broilers, layers, and native breeds) represented 5 Egyptian governorates (El-Qalubia, El-Behaira, El-Menofia, El-Gharbia, and Alexandria) in the period between March 2019 to February 2020 were screened and investigated for NDV by using RT-PCR via amplifying NDV full Fusion protein gene. The analysis of the full F-gene sequence revealed that our isolates were classified as genotype VII with the characteristic amino acids motif in the fusion protein cleavage site (RRQKRF) for the velogenic NDV (vNDV) strains. 5 representative isolates were sequenced for full fusion protein gene (sequence). The obtained sequences were submitted on GenBank: MW580389, MW580388, MW580387, MW566177, and MW590306. All five AOAV-1 isolates belonged to the NDV genotype classified as genotype VII.1.1 depending on full Fusion gene sequences. The pathogenicity of Newcastle Disease Virus (NDV) genotype VII.1.1 “NDV-CHICKEN-EGY-ALEX-NRC-2020” strain was investigated in combination with Infectious Bursal Disease Virus (IBDV) “IBDV/Egypt/Qalubia/17” and/or some commercial immunostimulants (Lector® and Orego®) in commercial broiler chickens. Our results indicated that, NDV is highly pathogenic virus especially when combined with IBDV infection in broiler chickens. In addition, immunostimulants are of low value against IBD and ND virulent viruses challenge. We 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) against challenge with NDV genotype VII 1.1 strain “NDV-CHICKEN-EGY-ALEX-NRC-2020”. All vaccination regimes were able to induce antibody levels for NDV after vaccination with varying titers. But, groups vaccinated with inactivated NDV genotype VII vaccines showed significant high antibody titers when compared with other groups.We concluded that vaccine genotypically- matched to challenge virus when used in combination with live attenuated NDV vaccines provided a significant protection against mortality and clinical disease when compared with other vaccination protocols.