Serological and molecular study of Newcastle disease in backyard chickens of Khorram Abad suburbs

Newcastle disease virus (NDV) is among major causes of disease and mortality in backyard chicken flocks in Iran and rapid and reliable diagnosis and determination of its causative agent is very important in veterinary diagnostic laboratories. In this study 178 serum samples were investigated backyard chicken flocks of 6 villages around Khorram Abad suburbs using hemaglutination inhibition. In addition, a few tissue samples were obtained from suspected flocks for virus isolation, using embryonated chicken eggs. Then, RT-PCR was established with RNA extracted from allantoic fluid samples using specific primers for F gene. All of the studied flocks and 65% of serum samples were positive for NDV antibodies. A total number of 3 isolates, detected in virus culture and RT-PCR, further were evaluated by restriction endonuclease analysis (REA) with BglІ. The results showed that the three isolates were not of lentogenic pathotype, confirmed in sequencing analysis. The extensive prevalence of ND antibodies among backyard chicken flocks of Khorram Abad and pathotype determination of the isolates are indications for circulation of velogenic NDV. The RT-PCR/REA technique in this study could be an accurate detection and pathotype differentiation method for NDV in backyard chickens.