A survey on presence of new strains of infectious bronchitis virus in some chicken farms of Egyptian Delta provinces during 2014

Abstract

Seven Infectious bronchitis virus (IBV) isolates were recovered from 62 broiler and layer chicken farmscollected from 4 Egyptian Delta provinces (Al Qalubia, Al Sharkia, Al Menofia and Al Gharbia) fromMay 2013 till July 2014 for drawing the epidemiological chart of distribution of IBV through theforementioned localities.The cardinal signs of the disease in layers were drop in egg production, withwatery albumen, inferior (pale-misshape shell) eggs, while in broilers were respiratory distress, renalurate deposition and mortality. Identification of IBV was by reverse transcriptase –polymerase chainreaction (RT-PCR) of RNA extracted from trachea and kidney tissues from freshly dead birds. Therewere 7/16 (about 43.7%) of selected suspected farms were positive for IBV with RT-PCR. A 600bphypervariable spike glycoprotein (S1) gene was amplified and sequenced to study genetic diversitybetween viruses. Sequence analysis was successfully performed with six isolates and failed with oneisolate. The phylogenetic analysis revealed that four isolates related to variant Israelin strains , three ofthem related to (IS/1494/06 ) and other one related to( IB isolate-variant -2 S1).Other two isolates ,oneof 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 andother nepherotropic form , 6 different vaccination programs of different commercial available IBvaccines. The results indicated that priming with M48 vaccine at 7 day old followed by IB Primer oneweek later gave the highest protection as assessed by clinical signs , weight loss , antibody titer andhistopathological lesion of trachea and kidneys