Molecular Analysis of Nucleocapsid Gene and ۳' Untranslated Regions of an Infectious Bronchitis Virus Isolate Originated from Broilers in Maragheh

Avian infectious bronchitis virus, has become one of the most problematic causes of economic losses in poultry farms. To effectively control the virus, monitoring and surveillance of circulating strains of virus in poultry farms is unavoidable.Internal organ samples of broilers with clinical signs of infectious bronchitis and two samples of the commonly used vaccine strains (۴/۹۱ and H۱۲۰) in Iranian poultry flocks were used in amplification of a ۱.۸ kbp fragment including nucleocapsid (N) gene and ۳′ untranslated region (UTR) using reverse transcription and polymerase chain reaction (RT-PCR) method. The amplified fragments were digested using restriction endonuclease enzyme, AluI. Then sequence similarity of the field isolate (Ma۱/۱۶ ) with previous isolates and reference strains of IBV was investigated. Also, phylogenetic relationship of Ma۱/۱۶ with other regions viruses were determined based on the sequence of two ۶۰۰ bp partial sequences of N gene using Mega۷ software.Seven strains of IBV were classified in two groups based on restriction fragment length polymorphism (RFLP) patterns of the N-۳´UTR fragment; all of five field isolates and vaccine strain ۴/۹۱ were clustered together. Ma۱/۱۶ had the most similarity with two other Iranian IBV isolates, Ur۱/۰۹ and MNS-۷۸۶۱-۱ (۹۱.۷ % and ۹۰ %, respectively) based on the ۶۰۰ N sequence of ۵´ end of the isolate. Nucleotide sequence of the ۶۰۰ N of ۳´ end of the amplified fragment in Ma۱/۱۶ isolate had the most similarity to the BJ strain (۸۶.۴%). Nucleocapsid gene could be an appropriate candidate in vaccine design strategies to IBV effective control. In addition, monitoring of circulating strains of IBV based on N-۳´UTR could be a helpful method in successfully controlling of IB disease in Iran.

کلیدواژه ها:

Infectious bronchitis virus ، N gene ، ۳´untranslated region ، RFLP