Molecular identification and Isolation of avian poxviruses from different bird species in Iran

Avian pox is a common viral disease among domestic and wild birds caused by different species of avipoxviruses of the family Poxviridae. Different avipoxviruses showed some degree of host specificity. In the present study 105 tissue samples were collected from different avian species with cutaneous or mucosal proliferative and/or necrotic lesions resembling pox. Molecular detection of poxviruses was conducted by a PCR targeting a conserved 4b gene. The PCR positive samples were also used for virus isolation by chorioallantoic membrane (CAM) inoculation of embryonated chicken eggs. Pox-like lesion was observed in five avian species and subsequently avipoxvirus was detected in 19 samples of backyard rural chickens (42.2%), 24 turkey samples (70.5%), a flock of commercial layer, a flock of commercial breeder turkey, four canaries (23.5%), two pigeons and two common mynahs (Acridotheres tristis). All viruses were propagated on CAM of chicken embryo and pock formation was evident except for two backyard chicken isolates. Phylogenetic study based on partial sequencing of the 4b gene revealed similarity of poxviruses originated from chicken and turkeys which all were in subclade A1. The only sequenced pigeon pox in the present study was in subclade A2. All passerine isolates including three canarypox viruses and two novel mynahpox viruses from common mynah were close together in subclade B2. Despite the history of vaccinations, avian pox was diagnosed in two commercial flocks in different provinces including a commercial layer and a commercial turkey breeder. Based on the results of present study, it was revealed that at least three different clades of avipoxviruses are causing avian pox in Galliformes, Columbiformes and Passeriformes in Iran. To the best of authors’ knowledge, this is the first report of molecular typing of mynahpox viruses in Iran.