الفهرس 
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Abstract
A total of 50 layer flocks of different breeds and ages were
collected from different localities within Sharkia governorate
during 2017 -2019 suspected to be infected with avian influenza
virus (AIV). Respiratory signs and/or decrease in egg production
were observed among the examined flocks.
The isolation and identification of AI viruses were carried
out on ECE using HA test and real time PCR as well as partial
sequence analysis of NA genes. Thirty five (70%) isolates were
hemagglutinating positive. The 35 hemagglutinating virus
isolates were identified as 16 (45. 71%) out of 35 were positive
for AIVs, out of 16 positive AIVs 4 flocks (25%) were H5
subtype positive, 9 flocks (56.25%) were H9 subtype positive
and 3 (18.75%) mixed flocks with H5 and H9 as well as 26
(74.28%) out of 35 were positive NDV by using real time PCR.
Three H9N2 viruses, two H5N8 viruses and 3 NDV were
partially sequenced. Sequence analysis revealed that the HA
protein of 3 H9 isolates harbor a proline-alanine-arginine-serine-
serine-arginine (PARSSR/G) motif, which is characteristic for
low pathogenicity in chickens. The three isolates showed that
they share 99-100% homology for HA and NA genes at amino
acid level. The percent of identity of 3 H9 isolates obtained in
this study with parent strain (A/Quail/Egypt/113413v/2011) was
95.6-96.2%.