Correlation of biological properties with glucan-binding protein B expression profile in Streptococcus mutans clinical isolates

Objective: Streptococcus mutans is known to be a primary causative agent of dental caries and its surface proteins have been investigated to specify their association with its virulence. Amongst those, 4 glucan-binding proteins (Gbps) are considered to be important factors due to their glucan-binding properties, of which GbpB has been shown to participate in cell-wall construction and cell separation. Design: We examined clinical isolates of S. mutans collected from the oral cavities of Japanese and Finnish subjects, and focused on the association of their GbpB expression profiles and biological properties related to virulence. Results: Western blot analysis of GbpB expression by the isolates revealed a variety of patterns. Strains that showed single and multiple bands were used to designate S and M type strains, respectively, whilst those with no GbpB expression were classified as N type. The distribution of GbpB expression patterns was shown to be quite different between the Japanese and Finnish isolates. Furthermore, the chain length and doubling time of the N type in both populations were significantly longer than those of the other types. Conclusion: Our results suggest variations in S. mutans GbpB expression patterns, which may have relationships with the virulence of S. mutans.