Rapid Detection of Avian Infectious Bronchitis Virus by Using Commercial Insulated Isothermal Polymerase Chain Reaction (iiPCR) and Enzyme-Linked Immunosorbent Assay (ELISA)

Infectious bronchitis (IB) is considered one of the most important poultry diseases worldwide. Many cases have been presented in Sri Lanka with similar clinical symptoms to those of IB in poultry belt areas. Therefore, the present study aimed to develop the IBV rapid detection methods using commercial insulated isothermal Polymerase Chain Reaction (iiPCR) and enzyme-linked immunosorbent assay (ELISA) in broilers, commercial layers, and backyard poultry flocks in Sri Lanka. Tracheal swabs and blood samples (n=413) were collected from vaccinated (n=107) and unvaccinated (n=306) birds exhibiting clinical signs attributable to IBV. Viral RNA was extracted from tracheal swabs and IBV was detected by iiPCR. Serum was separated from blood samples, and ELISA detected antibodies against IBV. It was reported that 46% (190/413) of birds were serologically positive for IBV by ELISA and 41.88% (173/413) of birds were positive for IBV by iiPCR. The total prevalence of IBV was 20.56% (22/107) of vaccinated and 49.34% (151/306) of unvaccinated poultry flocks by iiPCR. Furthermore, ELISA detected 30.84% (33/107) of vaccinated and 51.30% (157/306) of unvaccinated poultry flocks. Thus, IBV was more prevalent in unvaccinated birds comprised of backyard chickens and broilers in sampled areas. Moreover, the Batticaloa district had the highest prevalence of IBV (>75%). Thus, iiPCR assay could be used for rapid detection of IBV infection in clinical requirements.