Multilocus sequence analysis of Treponema denticola strains of diverse origin

• Published in: BMC microbiology Vol. 13; no. 1; p. 24
• Main Authors: Mo, Sisu, You, Meng, Su, Yvonne C F, Lacap-Bugler, Donnabella C, Huo, Yong-biao, Smith, Gavin J D, Leung, W Keung, Watt, Rory M
• Format: Journal Article
• Language: English
• Published: England BioMed Central 04.02.2013; BioMed Central Ltd; BMC
• Subjects: Asia; Bacterial Proteins - genetics; Bayesian analysis; Bioinformatics; Cell culture; Clinical isolates; Cluster Analysis; Computer programs; Confidence intervals; Data processing; Dentistry; Disease; DNA; DNA, Ribosomal - chemistry; DNA, Ribosomal - genetics; Evolution; FlaA protein; Gene polymorphism; Genes; Genetic algorithms; Genetic diversity; Genetic Variation; Genomes; Genomics; Globus pallidus; Hospitals; Humans; Infections; Infectious diseases; Medical research; Microbiology; MLSA; Molecular Sequence Data; Multilocus sequence analysis; Multilocus Sequence Typing; Netherlands; North America; Nucleotide sequence; Oral microbiota; Periodontal disease; Periodontal diseases; Phylogenetics; Phylogeny; Plaques; Positive selection; RecA protein; Recombination; RNA, Ribosomal, 16S - genetics; rRNA 16S; software; Spirochete; Spirochetes; Taxonomy; Treponema denticola; Treponema denticola - classification; Treponema denticola - genetics; Treponema denticola - isolation & purification; Treponema pallidum; Treponema vincentii; Asia; North America; Netherlands; Singapore
• ISSN: 1471-2180; 1471-2180
• DOI: 10.1186/1471-2180-13-24

The oral spirochete bacterium Treponema denticola is associated with both the incidence and severity of periodontal disease. Although the biological or phenotypic properties of a significant number of T. denticola isolates have been reported in the literature, their genetic diversity or phylogeny has never been systematically investigated. Here, we describe a multilocus sequence analysis (MLSA) of 20 of the most highly studied reference strains and clinical isolates of T. denticola; which were originally isolated from subgingival plaque samples taken from subjects from China, Japan, the Netherlands, Canada and the USA. The sequences of the 16S ribosomal RNA gene, and 7 conserved protein-encoding genes (flaA, recA, pyrH, ppnK, dnaN, era and radC) were successfully determined for each strain. Sequence data was analyzed using a variety of bioinformatic and phylogenetic software tools. We found no evidence of positive selection or DNA recombination within the protein-encoding genes, where levels of intraspecific sequence polymorphism varied from 18.8% (flaA) to 8.9% (dnaN). Phylogenetic analysis of the concatenated protein-encoding gene sequence data (ca. 6,513 nucleotides for each strain) using Bayesian and maximum likelihood approaches indicated that the T. denticola strains were monophyletic, and formed 6 well-defined clades. All analyzed T. denticola strains appeared to have a genetic origin distinct from that of 'Treponema vincentii' or Treponema pallidum. No specific geographical relationships could be established; but several strains isolated from different continents appear to be closely related at the genetic level. Our analyses indicate that previous biological and biophysical investigations have predominantly focused on a subset of T. denticola strains with a relatively narrow range of genetic diversity. Our methodology and results establish a genetic framework for the discrimination and phylogenetic analysis of T. denticola isolates, which will greatly assist future biological and epidemiological investigations involving this putative 'periodontopathogen'.