Molecular characterization of the heat shock protein 70 gene in Mycoplasma ovipneumoniae

Mycoplasma ovipneumoniae is a species of mycoplasma bacteria that commonly infects the respiratory tract, causing respiratory disease in sheep and goats worldwide. In the current study, the 70-kDa heat shock protein (Hsp70) gene was cloned, sequenced and analyzed in 14 clinical isolates of M. ovipneumoniae. Results showed that, compared to the reference Y98 strain, the open-reading frames (ORFs) of Hsp70 gene in all isolates were 1818 base pairs (bp). Three nucleotides of TCA were inserted at 1,776 bp, resulting in insertion of the amino acid glutamine at amino acid position 593. The neighbor-joining trees, constructed using the Hsp70 gene, exhibited that the closest genetic relationship occurred between M. ovipneumoniae and Mycoplasma hyopneumoniae, which was consistent with the one based on the whole genome comparisons between these two mycoplasma species. Therefore, these results suggest that the Hsp70 gene, rather than 16S ribosomal RNA, was suitable as a potential molecular marker for evaluating the genetic relationship of M. ovipneumoniae with other bacterial species.