Adhesion of Porphyromonas gingivalis Mutants and Wild-type Strains to HCAEC

Porphyromonas gingivalis is an important periodontal pathogen that is associated with adult periodontitis. Previous studies indicate that P. gingivalis may be involved in cardiovascular disease and atherosclerosis. Objective: The objective of this study was to determine the adherence phenotypes of various strains and mutants of P. gingivalis to HCAEC. The results of this study will help to identify P. gingivalis genes important for adherence. Methods: The growth rates of P. gingivalis strain W83 and its mutants were compared over a 36h period. Adherence assays were performed at 4^oC where P. gingivalis was in contact with HCAEC for 30min. Genomic DNA was immediately extracted for analysis. The P. gingivalis bound to HCAEC was quantified by Real-Time PCR using 16SRNA. Ribosomal 18SRNA was used as control. Results: All mutants had similar growth rates over 36h. P. gingivalis W83 and 381 showed the highest adherence to HCAEC. Strains A7436, AJW4, and ATCC33277 had decreased adherence compared to W83 (10.0%, 25.0%, and 40.5%, respectively; p<0.001). Adherence of mutant PG0280 (putative ABC transporter) was reduced compared to W83, but it was not statistically significant (p>0.05). However, mutants PG1321 (fhs), PG0686 (hypothetical protein), PG1286 (ftn), PG1683 (hypothetical protein), and PG0092 (putative ABC transporter) showed reduced adherence when compared to W83 (21.2%, 24.9%, 28.9%, 37.0%, and 66.3%, respectively; p<0.01). Conclusions: In this study, the growth rates were not affected by the mutations in the W83 strain. Different strains showed varying adherence phenotypes, which may be important in the virulence of these strains. All mutants, except PG0280, exhibited decreased adherence compared to W83, which may indicate that genes PG1321, PG0686, PG1286, PG1683, and PG0092 are important for adhesion of P. gingivalis to HCAEC. This project was funded by the UFCD Student Summer Research Fellowship, the Center for Molecular Microbiology, NIH grant DE 13545, and NIH-NIDCR grant T32 DE007200.