Abstract
Beijing lineage of Mycobacterium tuberculosis constitutes the most predominant lineage in East Asia. Beijing epidemiology, evolutionary history, genetics are studied in details for years revealing probable origin from China followed by worldwide expansion, partially linked to higher mutation rate, hypervirulence, drug-resistance, and association with cases of mixed infections. Considering huge amount of data available for 24-loci Mycobacterial Interspersed Repetitive Units-Variable Number of Tandem Repeats, we performed detailed phylogenetic and Bayesian population structure analyses of Beijing lineage strains in mainland China and Taiwan using available 24-loci MIRU-VNTR data extracted from publications or the SITVIT2 database (n = 1490). Results on genetic structuration were compared to previously published data. A total of three new Beijing clonal complexes tentatively named BSP1, BPS2 and BSP3 were revealed with surprising phylogeographical specificities to previously unstudied regions in Sichuan, Chongqing and Taiwan, proving the need for continued investigations with extended datasets. Such geographical restriction could correspond to local adaptation of these “ecological specialist” Beijing isolates to local human host populations in contrast with “generalist pathogens” able to adapt to several human populations and to spread worldwide.
Highlights
An earlier study[18], a recent study focusing on whole genome sequencing (WGS) based phylogeographical structure of Beijing isolates (n = 4987 strains from 99 countries, including 615 strains from China), showed congruent results for clusterization obtained by 24-loci MIRU-VNTRs and WGS19, defining a total six clonal complexes (CC1 to CC6) and a basal sublineage (BL7)
BSP1 and BSP2 isolates were predominant in Sichuan and Chongqing representing 94.25% (328/348) and 97.49% (194/199) of isolates respectively, while BSP3 isolates were exclusively found in Taiwan where they accounted for 52.96% (179/338) of all isolates
Based on phylogenetical and Bayesian population structure analyses of 24-loci MIRU-VNTRs, this investigation identified a total of five BSPs in China out of which three clonal complexes (BSP1, BSP2 and BSP3) were described for the first time when the data were compared to previous studies[19, 20]
Summary
The authors showed that CC1-CC5 comprised typical/modern Beijing strains as opposed to CC6 and BL7 which comprised atypical/ancestral Beijing variants, an observation further corroborated by a deeper branching of CC6 and BL7 in the genome-based trees[19]. This approach was considered relevant for further studying phylogenetic sublineages of Beijing strains in a limited collection from China (n = 302 clinical isolates)[20]. CH cases exclusively mapped with ubiquitous Beijing lineages, suggesting higher adaptability
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
