الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The H9N2 infection has been endemic in the Middle East including Egypt causing great economic losses. The virus has been detected in multiple avian species, pigs, and humans. Fifty-one tracheal swabs samples were collected from broiler chickens suffered from increased mortality rate from 6 governorates in Egypt during the period from 2014 to 2016. Real-time RT- PCR showed that 65% of samples were H9 subtype positive. Ten AI viruses (H9) were isolated from positive samples through embryonated chicken egg inoculation. Complete HA gene sequence for the ten isolates was performed. Phylogenetic analysis revealed that H9 viruses isolated in this study clustered together with other Egyptian strains isolated from 2011 till now and they fall in the Asian G1 like lineage. The isolated viruses share 91.2% - 99.8% amino acids identity in between and share 86.5% -89.9% amino acids identity with the prototype strain (A-Quail-HongKong-G1-97). Amino acids alterations in known antigenic sites and different glycosylation patterns were found. Many mammalian receptor signatures were found in receptor binding sites of isolated viruses. Sequence analysis of the HA cleavage site categorize this study isolates as low pathogenic as they lack multiple basic residues. Based upon serodiagnosis using ELISA and HI tests, H9 AI infection is a major contributor in increased broiler mortality rate and decreased egg production in breeder flocks. Infection with H9 AI may predispose to NDV and or IBV infections or vice versa. AI - ELISA test correlating with H9 – HI test was indicative for H9 AI infection. Control of H9 AIV infection is important due to its economic and potential zoonotic importance.