Diversity of Treponema denticola and Other Oral Treponeme Lineages in Subjects with Periodontitis and Gingivitis

• Published in: Microbiology spectrum 2021-10, Vol.9 (2), p.e0070121-e0070121
• Main Authors: Zeng, Huihui, Chan, Yuki, Gao, Wenling, Leung, W Keung, Watt, Rory M
• Format: Article
• Language: English
• Subjects: bacterial infection; Clinical Microbiology; Cohort Studies; etiology; Gingivitis - microbiology; Microbiota; Mouth - microbiology; Periodontal Diseases - microbiology; Periodontitis - microbiology; Phylogeny; Polymerase Chain Reaction; Research Article; RNA, Ribosomal, 16S - genetics; Species Specificity; spirochetes; Treponema - classification; Treponema - genetics; Treponema denticola; Treponema denticola - classification; Treponema denticola - genetics; Treponemal Infections - microbiology; UMP kinase
• ISSN: 2165-0497; 2165-0497
• DOI: 10.1128/Spectrum.00701-21

More than 75 species/species-level phylotypes belonging to the genus Treponema inhabit the human oral cavity. Treponema denticola is commonly associated with periodontal disease, but the etiological roles and ecological distributions of other oral treponemes remain more obscure. Here, we compared the clinical distributions of phylogroup 1 and 2 oral treponemes in subgingival plaque sampled from Chinese subjects with periodontitis (  = 10) and gingivitis (  = 8) via sequence analysis of the highly conserved housekeeping gene. Two PCR primer sets that targeted oral phylogroup 1 and 2 treponeme genes were used to construct plasmid clone amplicon libraries for each subject, and the libraries were sequenced for bioinformatic analysis. A total of 1,204 quality-filtered, full-length gene sequences were obtained from the cohort (median number, 61.5 cloned sequences per subject; range, 59 to 83), which were assigned to 34 genotypes (designated pyrH001 to pyrH034; 97% sequence identity cutoff). Eighteen genotypes (536 sequences) corresponded to phylogroup 1 treponeme taxa (including Treponema vincentii and Treponema medium). Sixteen genotypes (668 sequences) corresponded to T. denticola and other phylogroup 2 treponemes. Samples from periodontitis subjects contained a greater diversity of phylogroup 2 genotypes than did samples from gingivitis subjects (Mann-Whitney U test). One T. denticola genotype (pyrH001) was highly prevalent, detected in 10/10 periodontitis and 6/8 gingivitis subjects. Several subjects harbored multiple T. denticola genotypes. Nonmetric multidimensional scaling and permutational multivariate analysis of variance (PERMANOVA) revealed no significant differences in overall genotype compositions between periodontitis and gingivitis subjects. Taken together, our results show that subjects with periodontitis and gingivitis commonly harbor highly taxonomically diverse communities of oral treponemes. Periodontal diseases, such as periodontitis, are highly complex, multifactorial inflammatory infectious diseases affecting the gums and tooth-supporting structures. They are caused by chronic accumulations of dental plaque below the gum line that typically comprise hundreds of different bacterial species. Certain species of spiral-shaped bacteria known as treponemes, most notably Treponema denticola, are proposed to play key roles in the development and progression of periodontal disease. In our study, we characterized the genetic lineages of T. denticola