Contact-dependent regulation of a Tannerella forsythia virulence factor, BspA, in biofilms.

Tannerella forsythia is one of the periodontal organisms implicated in the development of periodontal diseases. The surface associated and secreted protein, BspA (encoded by the bspA gene), of this bacterium is an important virulence factor. The present study was carried out to examine the regulation of the bspA gene during biofilm growth and contact stimuli encountered in interbacterial interactions. The expression levels of the bspA transcript were determined by real-time RT-PCR approach. The levels of bspA transcript were found to be significantly reduced as a result of contact stimulus and in biofilm cells relative to planktonic cells. The results of our study suggest that the likely downregulation of the BspA protein in biofilms and following contact may have implications in pathogenesis as a plausible mechanism of evasion of host immune responses.