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"Pseudo-Beijing" : evidence for convergent evolution in the direct repeat region of Mycobacterium tuberculosis

Fenner, Lukas and Malla, Bijaya and Ninet, Béatrice and Dubuis, Olivier and Stucki, David and Borrell, Sonia and Huna, Thembela and Bodmer, Thomas and Egger, Matthias and Gagneux, Sebastien. (2011) "Pseudo-Beijing" : evidence for convergent evolution in the direct repeat region of Mycobacterium tuberculosis. PloS one, Vol. 6, H. 9 , e24737.

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Official URL: http://edoc.unibas.ch/dok/A6001992

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Abstract

Mycobacterium tuberculosis has a global population structure consisting of six main phylogenetic lineages associated with specific geographic regions and human populations. One particular M. tuberculosis genotype known as "Beijing" has repeatedly been associated with drug resistance and has been emerging in some parts of the world. "Beijing" strains are traditionally defined based on a characteristic spoligotyping pattern. We used three alternative genotyping techniques to revisit the phylogenetic classification of M. tuberculosis complex (MTBC) strains exhibiting the typical "Beijing" spoligotyping pattern.; MTBC strains were obtained from an ongoing molecular epidemiological study in Switzerland and Nepal. MTBC genotyping was performed based on SNPs, genomic deletions, and 24-loci MIRU-VNTR. We identified three MTBC strains from patients originating from Tibet, Portugal and Nepal which exhibited a spoligotyping patterns identical to the classical Beijing signature. However, based on three alternative molecular markers, these strains were assigned to Lineage 3 (also known as Delhi/CAS) rather than to Lineage 2 (also known as East-Asian lineage). Sequencing of the RD207 in one of these strains showed that the deletion responsible for this "Pseudo-Beijing" spoligotype was about 1,000 base pairs smaller than the usual deletion of RD207 in classical "Beijing" strains, which is consistent with an evolutionarily independent deletion event in the direct repeat (DR) region of MTBC.; We provide an example of convergent evolution in the DR locus of MTBC, and highlight the limitation of using spoligotypes for strain classification. Our results indicate that a proportion of "Beijing" strains may have been misclassified in the past. Markers that are more phylogenetically robust should be used when exploring strain-specific differences in experimental or clinical phenotypes.
Faculties and Departments:09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH) > Department of Medical Parasitology and Infection Biology > Tuberculosis Research (Gagneux)
UniBasel Contributors:Gagneux, Sebastien and Borrell, Sonia
Item Type:Article, refereed
Bibsysno:Link to catalogue
Publisher:PubMed Central
ISSN:1932-6203
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:08 Nov 2012 16:22
Deposited On:08 Nov 2012 16:10

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