الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
In the present study twenty nine samples representing twenty nine flocks of broilers, commercial layers and native breeds from five different governorates were examined for viral respiratory disease (NDV, H5N1, H9N2 and IBV) by RT-PCR after passaging in SPF ECE and testing with rapid HA test. 14 positive HA samples were scanned by RT-PCR which revealed 13 NDV, 6 H5N1 and 2 H9N2 positive samples in absence of IBV positive detection. Furthermore, detection of mixed infection between NDV & H5N1 or either NDV & H9N2 was concluded. Four isolates of NDV were sequenced and further phylogenetically analyzed demonstrating that these isolates were found related to VNDV genotype VIId that previously isolated in Egypt since 2012. In vivo vaccination protection study was carried out using different vaccination programs. 200-commercial layer chicks were divided into 4 groups of 50 birds; in which Groups (G1,G2&G4) vaccinated with live attenuated genotype II NDV vaccine at 10, 18 &120 days-old, in addition G1 were vaccinated with inactivated recombinant genotype VII NDV vaccine, while G2&G4 vaccinated with inactivated genotype II NDV vaccine at 14, 42 &120 days-old, respectively. Non-vaccinated group (G3) and chickens in G1, G2 were challenged at 185- days of age with VND (Genotype VII) (KM659400). Egg production percentages at challenge day were 86%, 86% and 87% in G1, G2 and G3, respectively. The results revealed that G1 showed significant protection against DROP in egg production at 2, 3 and 4 weeks (Wks) post challenge (pch) in compared with G2 by 79%, 82% and 87.4% Vs 72.5%, 69% and 82.6%, respectively. And viral shedding was significantly reduced in G1 in compared with G2 at 3 and 7days pch (30% and 10% Vs 80% and 40%), respectively. However, mortality percent was similar in G1 and G2 (2%) 4 Wks pch Vs (86%) in non-vaccinated challenged G3. In conclusion, our results demonstrated that used of genetic and antigenic homology vaccine with NDV genotype VII against challenge virus (genotype VII) is able to reduce shedding and DROP in egg production significantly in commercial layers.