S1 gene sequence analysis of a nephropathogenic strain of avian infectious bronchitis virus in Egypt

Abdel-Moneim, Ahmed S; El-Kady, Magdy F; Ladman, Brian S; Gelb, Jack

It is known that the most severe clinical response of IBV appears in very young chickens and severity is alleviated in older chickens [19, 20] . This fact explains the high mortality rate observed in 1-day-old chickens that experimentally inoculated with Egypt/F/03 compared to mortality pattern in the original flock (25-day-old chickens). The presence of acute interstitial nephritis on days 5 and 7 post infection indicated that Egypt\F\03 is a nephrogenic IBV. The microscopic findings of the renal tubules matched the general findings recorded with nephrogenic IBV strains [21, 22] . The microscopic findings in tracheal sections appeared similar to those recorded by [19, 21] including: loss of cilia, degenerative changes of the tracheal mucosa, irregular loss of epithelium, desquamation of the sloughed epithelium in the tracheal lumen and lymphocytic infiltration that ranged from focal aggregation to diffuse massive infiltration. Severe renal haemorrhages observed grossly and in hisopathological sections of birds dead after experimental infection with Egypt/F/03 denote that deaths resulted from acute renal failure. Our finding regarding the presence of petechial haemorrhages in larynx and thymus as well as severe congestion of liver, spleen and lungs in birds dead after IBV experimental infection is in agreement with [23, 24] who confirmed the presence of IBV viral antigens in such organs.