Genetic diversity of Mycobacterium bovis in dairy products and cattle tissues from northwest Iran using a 12-locus MIRU-VNTR approach

Mycobacterium bovis, the causative agent of bovine tuberculosis, poses public health risks through animal-derived products. This study evaluated the genetic diversity of M. bovis in 103 cattle tissue samples from tuberculin-positive or lesion-suspected slaughtered animals and 435 randomly collected dairy samples (335 milk, 100 traditional cheese) in northwest Iran. Positive samples were genotyped using a 12-locus MIRU-VNTR panel. Genetic diversity indices were 0.99 in tissue samples, 0.61 in milk, and 0.83 in cheese. The MTUB21 locus exhibited the highest allelic diversity (h = 0.73), whereas QUB26 showed the lowest (h = 0.16). Minimum spanning tree analysis revealed no well-supported source-specific clusters, indicating substantial allelic and genotypic diversity across sample types. Among the genotyped samples, 8.33% belonged to the caprae genotype, the most frequent lineage in this dataset. These findings provide insight into the population structure and genetic relationships of M. bovis in the region, supporting continued molecular surveillance within a One Health framework for tuberculosis control.