Isolation and molecular characterization of Mycoplasma ovipneumoniae associated with respiratory infection in sheep and goats in South India.

Mycoplasma ovipneumoniae is a significant pathogen causing atypical or non-progressive pneumonia in small ruminants, leading to considerable economic losses in the global small-ruminant industry. In this study, M. ovipneumoniae was isolated from sheep and goats showing respiratory symptoms in Tamil Nadu, India. A total of 200 samples, consisting of 186 nasal swabs and 14 lung tissue samples, were collected from animals exhibiting characteristic respiratory signs. The samples were cultured in Mycoplasma experience liquid media, and a color change indicated growth of mycoplasma, which was subsequently analyzed using a PCR assay targeting the 16 S rRNA gene specific to M. ovipneumoniae. Out of the 200 samples, 60 (30%) tested positive for M. ovipneumoniae in the PCR test. The broth cultures positive by PCR were further subjected to isolation on Mycoplasma Experience solid medium. Among the 60 PCR-positive cultures, 45 displayed typical "fried egg" micro-colonies, which were confirmed as M. ovipneumoniae through PCR. 16 S rRNA gene sequencing was conducted on seven of these isolates. The sequences were submitted to GenBank with accession numbers (PQ013702 to PQ013708). Phylogenetic analysis revealed that the seven isolates were closely related, forming two main clusters and grouping with Indian strains from the states of Kerala and Karnataka. This study highlights the prevalence of M. ovipneumoniae in small ruminants in Tamil Nadu and its genetic similarity with strains from neighboring regions. Molecular characterization of local isolates of M. ovipneumoniae could form the basis for development of rapid pen side diagnostic kit and vaccine for M. ovipneumoniae.