الفهرس 
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Abstract
One of the major problems of avian infectious bronchitis virus (IBV) is the frequent emergence of new variants. In the present study, 52 suspected farms from broiler chicken farms were collected during December 2012 to august 2014 from Damietta governorate districts these farms showed respiratory signs. There were 36/52 (65%) of suspected farms were positive for IBV with real time RT-PCR. Seven samples were selected from 36 IBV positive samples. The samples were inoculated in specific pathogen free (SPF) embryos for three blind successive passages and the hypervariable region of spike protein (SP1) was amplified and sequenced to study the genetic diversity between viruses. The phylogenetic analysis was carried out between the selected Seven isolates and other IBV from the Middle East. Seven isolates had identity percent between each other reach 100% ,close relationship with the Israeli variant (IS/1494) reached up to 89.3%. Also seven isolates had close relationship with D274 virus with identity 90.8%.