Filifactor alocis Virulence Factors Target Collagen Destruction Leading To Pathogenesis

Filifactor alocis, a Gram-positive anaerobic rod, is one of the most abundant bacteria identified in the periodontal pockets of periodontitis patients. Further, it is now considered one of the marker organisms associated with periodontal disease. We previously demonstrated that F. alocis has virulence properties that may enhance its ability to survive and persist in the periodontal pocket and may play an important role in infection-induced periodontal disease. There is a gap in our understanding of its pathogenicity. In other oral bacteria, collagen adhesion protein and other proteases are known to play important in colonization. In F. alocis we hypothesize the collagen adhesin protein (HMPREF0389_01006) and Protease (HMPREF0389_00122) may play a role in colonization, adhesion and destruction of host tissue. Objectives: To investigate the specific role of collagen adhesion protein(HMPREF0389_01006)and Protease(HMPREF0389_00122) in the survival and pathogenicity of F. alocis. Methods: Bioinformatics analysis and protein modeling were performed to evaluate the structural characteristics. Overlapping extension PCR was employed to generate isogenic mutants using the tetQ cassette. Phenotypic characterizations of the mutants, growth characteristics in solid and liquid media, response to oxidative stress were performed. Results: In silico analysis showed molecular relatedness to microbial surface components recognizing adhesive matrix molecules (MSCRAMMs) of other pathogenic bacteria. Domain architecture showed collagenase domain in Protease (HMPREF0389_00122) and a collagen C terminal collagen binding motif in the collagen adhesin protein (HMPREF0389_01006). The isogenic defective mutants showed white colonies in contrast to small translucent wild type colonies. In addition to reduced growth in the mutants under normal conditions, there was no variation in growth during oxidative stress compared to the wild type. Conclusion: The collagen adhesion protein and protease share molecular relatedness to major virulence factors of other bacteria. We anticipate variations in collagenase activity, biofilm formation and infectivity between the wild type and the mutants strains.