Differential expression and adherence of Porphyromonas gingivalis FimA genotypes

Abstract

SUMMARY Porphyromonas gingivalis is a primary pathogen involved in the initiation and progression of adult chronic periodontitis. Its colonization on oral surfaces is a necessary first step leading to infection. FimA, a subunit protein of major (long) fimbriae, is a well-known virulence factor. Based on its nucleotide sequence, FimA is classified into several genotypes. We compared here the transcriptional levels of the fimA gene in several P. gingivalis strains using real-time polymerase chain reaction analysis, fimbrial display on the P. gingivalis surface using transmission electronic microscopy, and the adherence competencies of P. gingivalis strains carrying different types of FimAs towards saliva and Streptococcus gordonii surfaces using mutagenesis analysis. We demonstrated differential expression of each fimA gene in these P. gingivalis strains. A correlation of the transcription level of fimA and binding activity of P. gingivalis was revealed. We show that P. gingivalis strains with genotype I and II of FimA are efficient in interaction with saliva or S. gordonii. This work highlights the important role of FimA type I and II in P. gingivalis attachment to oral surfaces.

Genetic Diversity in the Oral Pathogen Porphyromonas Gingivalis : Molecular Mechanisms and Biological Consequences

“…This ability to permanently colonize distinct niches implies that these bacteria have sophisticated mechanisms to adapt to the local environment. In vitro and animal model studies confirm the clinical observations: comparison of distinct P. gingivalis strains demonstrates extensive differences in behavior and pathogenic potential [28,30,31,39–52]. …”

“…The genetic variability of fimA probably has a significant influence on host–pathogen interactions, as the fimbriae mediate several key aspects of virulence, including manipulation of host cell responses to bacteria. In studies of P. gingivalis isolates from healthy and diseased individuals, fimA type Ib, II and IV are more commonly associated with periodontal disease, whereas types I and III are found primarily in isolates from healthy individuals [45,46,52,54]. The human studies have been confirmed by animal studies, which found that strains containing fimA type II and IV are more cytotoxic and invasive, while strains with fimA type I and III are less inflammatory and more likely to form localized selflimiting infections [55].…”

“…The human studies have been confirmed by animal studies, which found that strains containing fimA type II and IV are more cytotoxic and invasive, while strains with fimA type I and III are less inflammatory and more likely to form localized selflimiting infections [55]. The fimA type II allele is believed to contribute to improved virulence owing, in part, to its increased binding affinity for epithelial cell receptors compared with other fimA types [52,56]. …”

Identification of a Diguanylate Cyclase and Its Role in Porphyromonas gingivalis Virulence

“…Transmission electron microscopy of P. gingivalis was conducted as previously described (38). P. gingivalis strains ATCC 33277 and 1932E were grown anaerobically for 16 h in TSB.…”

Genetic exchange and reassignment in Porphyromonas gingivalis

“…Type II and IV fimA have significantly greater adhesive and invasive capabilities and are associated with more cytotoxic strains compared to other fimA type clones [15]. While type Ib, II and IV are most frequently associated with periodontitis [14–18], type I and III are less inflammatory and are associated with strains more likely to form localized self-limiting infections [19]. It has been suggested that the fimA type II allele confers a selective advantage in the advanced disease process thus ensuring its distribution throughout the P. gingivalis population [20].…”