Abstract

A survey of infectious bronchitis virus IBV genotypes in 25 commercial broiler flocks of various ages 20-35 days raised in Al-Behera and Kafr-Elsheikh governorates and suffering from respiratory symptoms and pathological changes in kidney associated with high mortality rate All flocks were vaccinated against IB disease Tissue samples trachea lung and kidney were collected aseptically from these flocks Then virus propagation was performed in embryonated SPF chicken eggs via allantoic sac inoculation Results of virus isolation trails from the collected organs revealed 15 IBV isolates 60 out of 25 flocks as judged by antigen detection in CAMs by the AGPT against reference IBV Beaudette antiserum after 2-5 chicken embryo serial passages However three of 15 IBV isolates were also positive by the slide HA test Moreover 5 flocks gave positive slide HA test and negative by the AGPT The other 5 flocks gave negative slide HA test and AGPT Then selected ten IBV field isolated strains in this study were characterized by RT-PCR all of ten selected isolates are positive for S1 gene and then sequence analysis of partial S1 spike glycoprotein gene of seven IBV field isolates in this study 11 15 21 13 19 22 24 were made The seven IBV field isolates showed 97 to 98 3 and 96 7 to 98 3 nucleotide sequence identity to IBV-CU-2-SP1 and Eg 12120s 2012 strain variant 2 like strain respectively