Antigenic variations of infectious bronchitis virus from broiler flocks in Al-Beheira governorate

ABSTRACT

Seventeen avian infectious bronchitis virus [IBV] isolates were isolated from broiler chickens showing respiratory and renal lesions. The isolated strains were characterized by real time reverse transcriptase polymerase chain reaction used for N gene, and then RT-PCR and sequence analysis of the hypervariable region 3 of the S1 spike glycoprotein gene of six isolates. Six isolates showed 87.15% to 89.71% and 87.27% to 90.82% amino acid sequence identity and 87.61% to 89.19% and 87.91% to 89.72% nucleotide sequence identity to the Egyptian variant 1 and the IS/885 strains, respectively. The six isolates formed a distinct phylogenetic group with the Ck/Eg/BSU-2/2011 and Ck/Eg/ BSU-3/2011 [Var 2]. Amino acid and nucleotide identities between the six Egyptian isolates and variant 2 [Ck/Eg/BSU-2/2011 and Ck/Eg/BSU-3/2011] ranged from 97.27% to 100% and 97.88% to 99.38%, respectively. The results indicate that the six isolates IBV/CK/Beh/101/013/S1, IBV/CK/Beh/204/013/S1, IBV/CK/Beh/105/013/S1, IBV /CK/Beh/1011/013/S1, IBV/CK/Beh/1017/013/S1, IBV/CK/Beh/2020/013/S1 can be considered a variant 2 as Ck/Eg/BSU-2/2011 and Ck/Eg/BSU-3/2011. This study demonstrates a constant evolution of IBV in Egypt that necessitates continuous monitoring to control the spread of infections, and the development and use of vaccines based on indigenous viruses