Porphyromonas gingivalisUses Specific Domain Rearrangements and Allelic Exchange to Generate Diversity in Surface Virulence Factors.
Porphyromonas gingivalisis a keystone pathogen of chronic periodontitis. The virulence ofP. gingivalisis reported to be strain related and there are currently a number of strain typing schemes based on variation in capsular polysaccharide, the major and minor fimbriae and adhesin domains of Lys-gingipain (Kgp), amongst other surface proteins.P. gingivaliscan exchange chromosomal DNA between strains by natural competence and conjugation. The aim of this study was to determine the genetic variability ofP. gingivalisstrains sourced from international locations over a 25-year period and to determine if variability in surface virulence factors has a phylogenetic basis. Whole genome sequencing was performed on 13 strains and comparison made to 10 previously sequenced strains. A single nucleotide polymorphism-based phylogenetic analysis demonstrated a shallow tri-lobed phylogeny. There was a high level of reticulation in the phylogenetic network, demonstrating extensive horizontal gene transfer between the strains. Two highly conserved variants of the catalytic domain of the major virulence factor the Kgp proteinase (KgpcatI and KgpcatII) were found. There were three variants of the fourth Kgp C-terminal cleaved adhesin domain. Specific variants of the cell surface proteins FimA, FimCDE, MfaI, RagAB, Tpr, and PrtT were also identified. The occurrence of all these variants in theP. gingivalisstrains formed a mosaic that was not related to the SNP-based phylogeny. In conclusionP. gingivalisuses domain rearrangements and genetic exchange to generate diversity in specific surface virulence factors.
Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, University of Melbourne VIC, Australia.
Stuart G
SG
Dashper
Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, University of Melbourne VIC, Australia.
Helen L
HL
Mitchell
Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, University of Melbourne VIC, Australia.
Christine A
CA
Seers
Victorian Life Sciences Computation Initiative Carlton, VIC, Australia.
Simon L
SL
Gladman
Victorian Life Sciences Computation Initiative Carlton, VIC, Australia.
Torsten
T
Seemann
Victorian Life Sciences Computation Initiative Carlton, VIC, Australia.
Dieter M
DM
Bulach
CSIRO Food and Nutrition Werribee, VIC, Australia.
P Scott
PS
Chandry
Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, University of Melbourne VIC, Australia.
Keith J
KJ
Cross
Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, University of Melbourne VIC, Australia.
Steven M
SM
Cleal
Oral Health Cooperative Research Centre, Melbourne Dental School, Bio21 Institute, University of Melbourne VIC, Australia.
Eric C
EC
Reynolds
Porphyromonas gingivalis; genetic diversity; periodontal pathogen; specific domain rearrangement; surface virulence factors