Molecular Detection of Avian Metapneumovirus in Semnan Broiler Farms

BACKGROUND: Avian Metapneumovirus (AMPV) causes mild to acute contagious infection of the upper respiratory tract in turkey and chicken with different mortality rate. OBJECTIVES: This study was aimed to molecular detection and subtyping of AMPV infection in broiler flocks using RT-PCR method in Semnan province on samples from 2016 to2020. METHODS: Sampling was carried out from the upper part of the trachea, choana, and sinuses of broiler chickens from the 85 broiler flocks. All flocks were more than 3 weeks of age. In total 10 swabs were taken from each flock, while each 5 were pooled as one sample (total two samples per flock). The samples were transferred to the laboratory for RNA extraction and RT-PCR amplification. RESULTS: Out of 85 tested broiler flocks, 30 (35.3%) were positive for AMPV using the Nd/Nx primer set. In addition, 28 positive samples were found to be of subtype B using the Ga/G12 primer set and 2 remaining positive samples were non-subtype B, probably A, C or D subtypes. CONCLUSIONS: Since AMPV vaccination was not performed in Semnan province, it can be concluded that some cases were infected with the natural viruses. Therefore, vaccination could be effective in controlling AMPV-induced respiratory distress.