Seven Infectious bronchitis virus (IBV) isolates were recovered from 62 broiler and layer chicken farms collected from 4 Egyptian Delta provinces (Al Qalubia, Al Sharkia, Al Menofia and Al Gharbia) from May 2013 till July 2014 for drawing the epidemiological chart of distribution of IBV through the forementioned localities.The cardinal signs of the disease in layers were drop in egg production, with watery albumen, inferior (pale-misshape shell) eggs, while in broilers were respiratory distress, renal urate deposition and mortality. Identification of IBV was by reverse transcriptase –polymerase chain reaction (RT-PCR) of RNA extracted from trachea and kidney tissues from freshly dead birds. There were 7/16 (about 43.7%) of selected suspected farms were positive for IBV with RT-PCR. A 600bp hypervariable spike glycoprotein (S1) gene was amplified and sequenced to study genetic diversity between viruses. Sequence analysis was successfully performed with six isolates and failed with one isolate. The phylogenetic analysis revealed that four isolates related to variant Israelin strains , three of them related to (IS/1494/06 ( and other one related to( IB isolate-variant -2 S1).Other two isolates ,one of them related to classical vaccinal strain (H120) and other related to variant vaccinal strain (D274). Using two IBV isolates related to IS/1494/06 as challenging viruses one of them respiratory form and other nepherotropic form , 6 different vaccination programs of different commercial available IB vaccines. The results indicated that priming with M48 vaccine at 7 day old followed by IB Primer one week later gave the highest protection as assessed by clinical signs , weight loss , antibody titer and histopathological lesion of trachea and kidneys. |
