Lineage variability in surface components expression within Porphyromonas gingivalis

Area of Science:

• Oral microbiology
• Bacterial pathogenesis
• Genomics

Background:

• Porphyromonas gingivalis is a key periodontopathogen with varying virulence.
• Capsule and fimbriae are critical virulence factors for P. gingivalis, aiding colonization and immune evasion.
• The expression of these factors can differ among strains, suggesting potential genetic underpinnings.

Purpose of the Study:

• To investigate the association between P. gingivalis genetic clusters/genotypes and the production of capsule and fimbriae.
• To determine if specific genotypic profiles correlate with the presence or absence of these key virulence factors.

Main Methods:

• Phenotypic analysis of capsule (K) and fimbriae (F) production in 16 P. gingivalis isolates using microscopy and TEM.
• Genotyping using NotI macrorestriction fragments analysis via Pulsed-Field Gel Electrophoresis (PFGE).
• Multi-locus sequence typing (MLST) based on seven house-keeping genes.

Main Results:

• Four phenotypic profiles were observed: F(+)K(+), F(-)K(+), F(+)K(-), and F(-)K(-).
• PFGE identified 14 distinct clusters, and MLST revealed significant genetic diversity.
• No significant association was found between P. gingivalis genetic clusters and the production of capsule or fimbriae.

Conclusions:

• Current genotyping methods (PFGE and MLST) cannot differentiate P. gingivalis isolates based on capsule and fimbriae production.
• Recombination appears to play a significant role in the variable expression of capsule and fimbriae in P. gingivalis.
• The genetic basis for virulence factor expression in P. gingivalis is more complex than simple genotypic clustering.