Hemotropic Mycoplasma in cattle and Asian water buffalo in Thailand: Revealing globally distributed sequence types and regional genetic diversity

Hemotropic mycoplasmas, particularly <i>Mycoplasma wenyonii</i> and "<i>Candidatus</i> Mycoplasma haematobovis", are increasingly recognized as emerging vector-borne pathogens of veterinary importance in cattle and buffalo. Due to their complex epidemiology and the limited understanding of their pathogenic mechanisms, hemoplasma infections in large ruminants are often underdiagnosed and underreported, especially in resource-limited settings. This study investigated the genetic diversity and phylogenetic relationships of hemotropic <i>Mycoplasma</i> species in blood samples collected from cattle and buffalo across seven provinces in Thailand between 2016 and 2023. A total of 422 samples (214 from cattle and 208 from buffalo) were analyzed, with 373 testing positive for hemotropic <i>Mycoplasma</i> DNA. Phylogenetic analyses of the 16S and 23S rRNA gene sequences revealed two distinct clades corresponding to <i>M. wenyonii</i> and "<i>Ca</i>. M. haematobovis". Most sequences clustered with <i>M. wenyonii</i> strains from multiple countries, while a smaller subset grouped with "<i>Ca.</i> M. haematobovis" strains. Intraspecific sequence similarity among <i>M. wenyonii</i> 16S rRNA gene sequences ranged from 97.29% to 100%, whereas "<i>Ca.</i> M. haematobovis" sequences showed similarities ranging from 99.75% to 100%. Interspecific similarity between the two species ranged from 83.48% to 84.34%. For the 23S rRNA gene sequences, <i>M. wenyonii</i> exhibited intraspecific similarity levels ranging from 90.94% to 100%, while "<i>Ca</i>. M. haematobovis" sequences demonstrated 99.53% similarity; interspecific similarity for this gene ranged from 76.69% to 77.34%. We identified 11 nucleotide sequence types (ntSTs) for <i>M. wenyonii</i>, with ntST10 being the most widely distributed, shared among isolates from Cuba, Thailand, Japan, and Brazil. The single "<i>Ca</i>. M. haematobovis" sequence type detected in this study clustered within ntST7, alongside sequences from Cuba, Malaysia, Brazil, Turkey, Kyrgyzstan, and Japan. These findings highlight the substantial genetic diversity and broad geographical distribution of hemotropic <i>Mycoplasma</i> species in Thailand and emphasize the critical importance of molecular screening for managing the risk of pathogen transmission within livestock populations.