Molecular characterization of the hypervariable regions of S1 gene of infectious bronchitis virus isolates

A preliminary study was conducted for the detection of the infectious bronchitis virus circulating among the poultry flocks of Kerala employing a reverse transcriptase polymerase chain reaction, where, a high prevalence of the virus was reported. The present study is the first comprehensive study pertaining to the molecular characterization of hypervariable regions of the S1 gene of IBV in Kerala. The positive samples were sequenced with primers targeting the three hypervariable regions of the S1 subunit of spike gene. It was observed that the isolates of Kerala shared more than 95% similarity with isolates from different parts of India. On phylogenetic analysis of hypervariable regions 1 and 2, all the Kerala isolates clustered with isolates from other parts of the country. Phylogenetic analysis of the hypervariable region 3 revealed that the Kerala isolates branched separately from the isolates belonging to different parts of India. The study advocated the need of an area specific vaccine in Kerala, employing the potential candidate vaccine strain isolated in the study.