Dominant modern sublineages and a new modern sublineage of Mycobacterium tuberculosis Beijing family clinical isolates in Heilongjiang Province, China

- 9 out of the 10 SNP loci displayed polymorphisms but locus 1548149 did not.
- 92.8% of the isolates in Heilongjiang Province are the modern sublineages.
- ST10 is the most prevalent sublineage.
- A new ST accounting for 4% of the Beijing family isolates was found for the first time in the world.
- Each new ST isolate showed a unique VNTR pattern, and none were clustered.

Mycobacterium tuberculosis Beijing family includes a variety of sublineages. Knowledge of the distribution of a certain sublineage of the Beijing family may help to understand the mechanisms of its rapid spread and to establish an association between a certain genotype and the disease outcome. We have previously found that M. tuberculosis Beijing family clinical isolates represent approximately 90% of the clinical isolates from Heilongjiang Province, China. To clarify the distribution of M. tuberculosis Beijing family sublineages in Heilongjiang Province, China and to investigate the regularity rule for their evolution, we examined single nucleotide polymorphisms (SNPs) of 250 M. tuberculosis Beijing family clinical isolates using 10 SNP loci that have been identified as appropriate for defining Beijing sublineages. After determining the sequence type (ST) of each isolate, the sublineages of all M. tuberculosis Beijing family isolates were determined, and phylogenetic analysis was performed. We found that 9 out of the 10 SNP loci displayed polymorphisms, but locus 1548149 did not. In total, 92.8% of the isolates in Heilongjiang Province are modern sublineages. ST10 is the most prevalent sublineage (ST10 and ST22 accounted for 63.2% and 23.6% of all the Beijing family isolates, respectively). A new ST, accounting for 4% of the Beijing family isolates in this area, was found for the first time. Each new ST isolate showed a unique VNTR pattern, and none were clustered. The present findings suggest that controlling the spread of these modern sublineages is important in Heilongjiang Province and in China.