Infectious bronchitis (IB), caused by the IB virus (IBV), is a highly contagious disease and results in a
significant economic loss to the commercial chicken industry all over the world. The emergence of new
variants constitutes a major problem of avian infectious bronchitis virus (IBV). A recent increase in
IBV-suspected outbreaks in the vaccinated chicken broiler farms in kafrelsheikh governorate, prompted
to investigate the molecular characters of the circulating IBV. In present study, Tissue samples (trachea,
lung and kidney) were collected aseptically from these farms; samples were examined for IBV by
conventional PCR. Nine samples showed positive for IBV. Trails for virus isolation from the collected
organs were carried out by inoculating tissue suspensions into embryonated specific pathogen-free
(SPF) eggs via allantoic sac inoculation. The allantoic fluids were collected and tested using RT-PCR
for IBV S1 gene. Nine samples gave 570 bp amplicon. Sequence analyses of partial S1 spike
glycoprotein gene of three IBV field isolates in this study were made. The phylogenic tree was
constructed; showed that the three recent IBV field isolates showed 93% to 95 % nucleotide sequence
identity to IBV-CU-2-SP1, Eg/12120s/2012 and IBV/Egypt/0113/VIR9715/2012 strains.