Epidemiology of Avian Infectious Bronchitis Virus Genotypes in Iran (2010-2014).

Infectious bronchitis virus (IBV) in vaccinated chicken flocks continues to cause enormous economic losses to the poultry industry in Iran. A molecular surveillance of IBV genotypes involved in outbreaks of disease was performed. Specimens of trachea, kidney, and cecal tonsil were collected from 250 suspected flocks (more than 2500 samples) and identified between 2010 and 2014. Partial spike glycoprotein gene sequences revealed seven distinct genotypes, including Mass, 793/B, IS720, Variant 2, QX, IR-I, and IR-II, to be circulating in the chicken farms. The majority of flocks (67.6%) experienced infection with an IBV variant unrelated to the vaccine strains. These variants displayed homologies ranging from 54.1% to 78.5% and from 53% to 86% with H120 and 4/91, respectively. These findings reveal the existence of IBV variants genetically different from the vaccine strains currently in use and explain the outbreaks of disease observed in the field. The current work constitutes the first comprehensive survey of IBV in Iran and emphasizes the need for continuous monitoring and rethinking of current preventative measures.