Veterinary Research Forum

Abstract 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.

Abstract This study was conducted in West Azerbaijan province, Iran (37°27'18.022" N, 45°0'0" E) to investigate the genotyping and phylogenetic characterization of Mannheimia haemolytica in cattle and buffaloes from November 2022 to January 2024. Mannheimia haemolytica is a bacterium known to cause pasteurellosis pneumonia, a respiratory disease in ruminants, such as cattle and sheep. This is one of the main causes of economic losses in the feedlot industry. In addition to the deaths, treatment costs are also significant. The lung and nasal swab samples were collected from 378 cattle and buffaloes. The M. haemolytica was detected in 32 (8.46%) of the samples, with a notably higher isolation rate from lung tissue (56.25%; n = 18) compared to the nasal swabs (43.75%; n = 14). Interestingly, the study also revealed a seasonal pattern, with the highest isolation rates observed during January, February, and March. Multi-locus sequence typing demonstrated that all isolates belonged to sequence type 1 (ST1) within clonal complex 28. This finding is consistent with the global prevalence of ST1 in bovine isolates, indicating widespread distribution. Phylogenetic analysis revealed a strong correlation between ST1 and STs 30 and 54, highlighting the prevalence of ST1 in M. haemolytica among ruminants in West Azerbaijan, Iran. Further research is needed to investigate its potential for causing disease and its transmission pattern.