Faculty of Veterinary Medicine, Urmia University Veterinary Research Forum 2008-8140 17 7 2026 07 01 Molecular identification of Avibacterium paragallinarum isolates from backyard and commercial layer chickens in Iran 489 496 737465 10.30466/vrf.2025.2064747.4815 EN Chnoor Poorshamohammad Department of Avian Health and Diseases, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran Mohammad Hassanzadeh Department of Avian Health and Diseases, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran 0000-0003-2288-417X Abbas Nouri Department of Avian Disease Research and Diagnostics, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran Mohammad Hassan Bozorgmehrifard Department of Avian Health and Diseases, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran Mohammad Abdoshah Department of Avian Disease Research and Diagnostics, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran Fereshteh Sabouri Department of Avian Disease Research and Diagnostics, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran Mohsen Bashashati Department of Avian Disease Research and Diagnostics, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran 0000-0003-1174-4761 Journal Article 2025 07 10 Infectious coryza, caused by Avibacterium paragallinarum, poses a significant economic threat to the global poultry industry. Although infectious coryza is present in Iran, there is limited molecular data characterizing the circulating strains, particularly regarding key hemagglutinin genes such as hagA. This study aimed to investigate the genetic diversity and phylogenetic relationships of the Av. paragallinarum isolates recovered from commercial and backyard poultry in Iran by sequencing the hagA gene and comparing the findings with those of global strains. Twenty-three Av. paragallinarum isolates collected from Iranian poultry farms underwent PCR amplification and sequencing of the hagA gene. Nucleotide and deduced amino acid sequences were analyzed for homology, subjected to BLAST searches, and used for phylogenetic reconstruction. The isolates showed high sequence identity, ranging from 94.10 - 99.90% at the nucleotide level and 92.10 - 100% at the protein level. Phylogenetic analysis classified the isolates into five distinct clusters (Iran-1 to Iran-5). The largest cluster (Iran-1) showed a strong affiliation with strains from China and India, whereas the other isolates clustered with strains from South Korea, Germany, and Japan. Notably, the Iran-5 group exhibited high similarity to a non-typable strain from USA. Additionally, eight isolates encoded truncated HagA proteins, each consisting of 344 rather than 345 amino acids. This study demonstrates the circulation of genetically diverse Av. paragallinarum strains in Iran. These findings highlight the need for further molecular investigations to improve control measures and assess the efficacy of the vaccines currently used in the country.

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