Genomic deletions classify the Beijing/W strains as a distinct genetic lineage of Mycobacterium tuberculosis.
Beijing/W strains of Mycobacterium tuberculosis are geographically widespread and hypervirulent. To enhance our understanding of their origin and evolution, we sought phylogenetically informative large sequence polymorphisms (LSPs) within the Beijing/W family. Comparative whole-genome hybridization of Beijing/W strains revealed 21 LSPs, 7 of which were previously unreported. We show that some of these LSPs are unique event polymorphisms that can be used to define and subdivide the Beijing/W family. One LSP (RD105) was seen in all Beijing/W strains and thus serves as a useful marker for the identification of this family of strains. Additional LSPs (RD142, RD150, and RD181) further divided this family into four monophyletic subgroups, demonstrating a deeper population structure than previously appreciated. All Beijing/W strains were also observed to have an intact pks15/1 gene that is involved in the biosynthesis of a phenolic glycolipid, a putative virulence factor. A simple PCR assay using these Beijing/W strain-defining deletions will facilitate molecular epidemiological studies and may assist in the identification of the molecular basis of phenotypes associated with this important lineage of M. tuberculosis.
Division of Infectious Diseases and Geographic Medicine, Stanford University Medical Center, Stanford, California 94305, USA. a.tsolaki@imperial.ac.uk
Anthony G
AG
Tsolaki
Sebastien
S
Gagneux
Alexander S
AS
Pym
Yves-Olivier L
YO
Goguet de la Salmoniere
Barry N
BN
Kreiswirth
Dick
D
Van Soolingen
Peter M
PM
Small
D001483:Base Sequence; D016680:Genome, Bacterial; D006801:Humans; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000145:classification* / Q000235:genetics*; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D011110:Polymorphism, Genetic; D017384:Sequence Deletion