Abstract
Brucellosis is one of the important zoonotic in the livestock industry and public health. The aim of the present study This study aimed at the detection of Brucella spp. directly from specimens of dairy cows and molecular characterization of Brucella spp. understanding their virulence attributes. A total of 110 samples were collected from Mumbai and Pune districts, encompassing various sources such as placental cotyledons, fetal abomasal content, fetal vitals, vaginal swabs, serum, and milk, all from cattle suspected of brucellosis. A total of 24 milk and serum samples were tested for Brucella antibodies, and it was found that 24 (57.14%) and 19 (45.23%) samples were positive by MRT and RBPT tests, respectively. Employing molecular techniques, including PCR assays targeting specific genes, facilitated the detection and identification of Brucella spp. and Brucella abortus directly from specimens of dairy cattle. Among these, 17 out of 110 samples tested positive for Brucella spp (15.45%), with 5 out of 17 confirmed to be Brucella abortus (29.39%). Subsequent sequencing and phylogenetic scrutiny validated that all 5 samples belonged to the Brucella abortus species. These samples shared geographic origins and were aligned within the same lineage as previous Brucella abortus isolates submitted to Gene Bank from Mumbai, India. The presence of virulence genes virB, bvfA in all 5 Brucella abortus samples was noted, by PCR assay targeting specific genes. The identification of virulent genes in the positive samples confirms their pathogenicity concerning their survival, colonization, and evasion of the animal immune response. This underscores the necessity for ongoing research to formulate effective disease management strategies.