Typing of field isolates of Infectious bronchitis virus from Kerala using reverse transcriptase polymerase chain reaction-restriction fragment length polymorphism analysis

Poultry farming is one of the booming industries in India. But the sector is still the victim of menace caused by various viruses. Infectious bronchitis is one such disease, which cause economic loss to the industry worldwide. In Kerala, vaccination against the disease is not strictly followed and there are frequent reports of the disease outbreaks from different parts of the state. Hence, monitoring of Infectious bronchitis virus strains circulating in the state is necessary. Pooled tissue samples were collected from ailing/recently dead birds with symptoms/lesions suggestive of infectious bronchitis, from various parts of the state. Reverse transcriptase polymerase chain reaction targeting hypervariable region 3 was done to detect the virus from tissue samples followed by virus inoculation in embryonated chicken egg. The ribonucleic acid extracted from allantoic fluid was used for reverse transcriptase polymerase chain reaction targeting S1 subunit of S gene. The representative amplicons were then subjected to nucleotide sequencing and restriction fragment length polymorphism analysis. Thirty-two samples were found to be positive by RT-PCR. Restriction fragment length polymorphism analysis of S1 subunit of S gene generated restriction patterns similar to vaccine strain, Massachusetts type.