Abstract

Infectious bronchitis (IB) is one of the important contagious diseases in the poultry industry, through which genome alternation can lead to a newly modified IB strain. Many IB outbreaks in recent years have occurred in Babylon, Iraq, even with the implementation of a vaccination program. Therefore, the current study aimed to investigate the IB virus genome to identify the circulating strain. In this regard, any respiratory signs in broiler chickens were initially diagnosed as IB in seven farms of Babylon province, Iraq, from January to March 2021 leading to high economic loss. A total of 25 serological tests indicated infection with IB disease. Then, Flinders Technology Associates cards loaded with samples were sent to AniCon Labor GmbH Laboratory diagnostic in Germany for identification by extraction and sequencing the fragment of the S1 spike protein-coding gene. In the next step, the viral sequences were compared with the globally known strains of vaccines and field strains in the GenBank database using the NCBI. The results indicated a high similarity of the strain MZ520128 in the current investigation with IQ1 (MH747093.1) and Israeli (IS/1494/06) strains by 98.3% and 81.8%, respectively. Furthermore, the similarity of the current isolate with vaccine strains was reported as 24-43%. This variance among the current isolates with other strains could explain the reasons the vaccination strains and programs provide poor protection against the field infected by IBV. The current isolate of MZ520128 was a circulating pathogen with economic losses and the commercially available vaccine did not provide enough level to stand against the incidence of the disease.