Identification and Genomic Analysis of a Pathogenic Strain of Mycoplasma hyopneumoniae (TB1) Isolated from Tibetan Pigs.

The present study aims to identify the species and strains of Mycoplasma hyopneumoniae isolated from Tibetan pigs (Mh TB1) at the genetic level for understanding the basis of its pathogenicity. Mh TB1 was isolated from the consolidated lungs of Tibetan pigs by liquid culture and agar plate colony method. Polymerase chain reaction (PCR) amplification of the 16S recombinant DNA (rDNA) conservative sequence and a species-specific gene (P36) of Mh provided species confirmation. PCR products were imaged on gels and shotgun sequencing was performed. DNA sequences were compared for assessing genetic similarity between Mh TB1 and Mh reference strains in the GenBank database. The isolated strains were >98% similar to the Mh reference strains. Genomic analysis revealed significant sequence conservation between Mh TB1 and the reference strains; however, differential genes were more prevalent in Mh TB1 than in other reported strains. Therefore, we concluded that Mh is a major pathogen of Tibetan pigs that cause enzootic pneumonia. The Mh TB1 strain harbors more genes and specific virulence factors, consistent with its plateau-related adaptability to hypoxia and virulence. Differential gene analysis revealed gene variations in the inclement plateau environment, enriched gene pool, and plateau adaptability of the Mh TB1 strain, which will be important for vaccine development.