The role of Newcastle disease virus in respiratory syndromes of broiler flocks in Khuzestan and Isfahan provinces, Iran

Newcastle disease, as one of the most important diseases of the poultry industry, has many economic losses. The aim of this study was to investigate the role of Newcastle disease virus in respiratory syndromes of broiler flocks in Khuzestan and Isfahan provinces. For this purpose, tissue samples (trachea, lung, and cecal tonsils) were taken from ten dead birds of 20 broiler farms with respiratory symptoms in different regions of these two provinces. Samples were inoculated into 9 to 11 days old embryonated chicken eggs. The RT-PCR was performed to detect Newcastle disease virus on allantoic fluid. Out of 20 studied flocks, the virus was isolated and identified in nine flocks. The 330 base pair nucleotide sequence in the F gene virus cleavage site was examined in 9 isolates. The results of RT-PCR test showed that Newcastle disease virus was isolated from respiratory syndromes in 50% of broiler flocks in Khuzestan province and 40% of broiler flocks in Isfahan province. Of the 9 isolates, 3 were in genotype II and 6 were in genotype VIId of class II Newcastle disease virus, and isolates of both genotypes were present in both provinces. The variety of VIId isolates found in Khuzestan province was more than Isfahan province. Isolates belonging to genotype II in this study were similar to Pakistani, Chinese and Nigerian strains, and other isolates were similar to previous Iranian strains.