Differences in the population of genetics of Mycobacterium tuberculosis between urban migrants and local residents in Beijing, China.
BACKGROUND
Currently, migration has become one of the risk factors of high burden of tuberculosis in China. This study was to explore the influence of mass migration on the dynamics of Mycobacterium (M.) tuberculosis in Beijing, the capital and an urban area of China.


METHODS
Three hundred and thirty-six M. tuberculosis strains from the Changping district, where the problem of urban migrants was more pronounced than in other Beijing regions, were genotyped by Spoligotyping, large sequence polymorphisms (LSPs 105 and 181), and variable number tandem repeat (VNTR) typing. Based on the genotype data, the phylogeny of the isolates was studied.


RESULTS
In Changping district, the proportion of Beijing lineage M. tuberculosis isolates amounted to 89.0% (299/336), among which 86.6 % (252) belonged to the modern lineage. The frequency of modern Beijing lineage strains is so high (around 75% (252/336)) that associated risk factors affecting the tuberculosis epidemic cannot be determined. The time to the most recent common ancestor (TMRCA) of the Beijing lineage strains was estimated to be 5073 (95% CI: 4000-6200) years. There was no significant difference in the genetic variation of Beijing isolates from urban migrants and local residents.


CONCLUSIONS
The clone of modern Beijing lineage M. tuberculosis, which is dominant in the Beijing area, most likely started to expand with the five thousand-year-old Chinese civilization. In the future, with the urbanization in the whole of China, modern Beijing lineage M. tuberculosis may gain the larger geographical spread.
National Tuberculosis Clinical Lab of China, Beijing Tuberculosis and Thoracic Tumor Research Institute; Beijing 101149, China.
Guang-Ming
GM
Dai
Zhi-Guo
ZG
Zhang
Peng-Ju
PJ
Ding
Qian
Q
Zhang
Li
L
Wang
Li-Xia
LX
Wang
Dick
D
van Soolingen
Hai-Rong
HR
Huang
Wei-Min
WM
Li
Chuan-You
CY
Li
D002681:China; D005828:Genetics, Population; D005838:Genotype; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000235:genetics*; D010802:Phylogeny; D014171:Transients and Migrants