Background and Aims: Global epizootic distribution of HPAI H5N8 (Clade 2.3.4.4) in poultry and wild birds was demonstrated after 2010. HPAI virus is a major concern in the birds and poultry industry and global human health. Wild migratory birds and their link to backyard birds play a critical role in spreading HPAI and creating genetic reassortment. Materials and Methods: In this study in 2018, HPAI H5N8 was isolated from Backyard poultry (turkey) in East Azerbaijan Province, Iran. Three reports of outbreaks were submitted. The first outbreak was in a village, Sholebaran, and the second was in a Livestock market in Bahman, and the third was in another Village, Yaghbastloo. Tracheal and pancreas tissue samples were obtained from 10 dead birds, and 300 susceptible domestic birds include in the turkey and chickens. Samples\\\' diagnosis was based on real-time reverse transcriptase PCR (RRT-PCR) and partial HA gene sequencing. Turkey samples were positive and characterized as H5N8. Results: Phylogenetic analysis result based on a partial HA gene revealed that the Iranian HPAI H5N8 virus in our study, belong to the subgroup clade 2.3.4.4 and cluster within group B. Conclusion: These findings indicate that it provides new insights into the evolution and spread of H5N8 in Iran; based on these results, we have to recognize an improper monitoring protocol for reducing the reassortment of them. Therefore, we could prevent HPAI from circulating.

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