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