Molecular detection and phylogenetic properties of isolated infectious bronchitis viruses from broilers in Ahvaz, southwest Iran, based on partial sequences of spike gene

Infectious bronchitis (IB) is a highly contagious disease involving mostly upper respiratory tract in chickens, leading to significant economic losses in the poultry industry worldwide. One of the major concerns regarding to IB is the emergence of new types of infectious bronchitis viruses (IBVs). The purpose of this study was to identify the IBVs isolated from Iranian broiler chickens with respiratory symptoms. Twenty-five broiler flocks around Ahwaz (southwest of Iran) were examined for IBV. The specimens including trachea, lung, liver, kidney, and ceacal tonsil, were collected from diseased birds and inoculated into chicken embryonated eggs. Harvested allantoic fluids were subjected to reverse transcription polymerase chain reaction (RT-PCR) using primers in order to amplify spike ۱ (S۱) gene of IBV. The RT-PCR products of four IBV isolates were sequenced. The results showed that from ۲۵ examined flocks with respiratory disease, ۱۲ flocks (۴۸.۰۰%) were positive for IBV. In phylogenetic analysis, our isolates were closely related to the QX-like viruses such as PCRLab/۰۶/۲۰۱۲ (Iran), QX, HC۹, HC۱۰, CK/CH/GX/NN۱۱-۱, CK/CH/JS/YC۱۱-۱, CK/CH/JS/۲۰۱۰/۱۳, CK/CH/JS/۲۰۱۱/۲ (China), QX/SGK-۲۱, QX/SGK-۱۱ (Iraq) with nucleotide homology up to ۹۹.۰۰%. This study indicates the role of IBVs in the respiratory disorders of broiler flocks located in southwest Iran, and also the existence of a variant of IBV, which is distinguishable from the other Iranian variants.

کلیدواژه ها:

Infectious bronchitis virus ، Iran ، QX-like viruses ، S۱ gene