mutans streptococci のビルレンス因子の発現に及ぼす継代培養の影響
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概要
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The fresh isolates of mutans streptococci (two strains of Streptococcus mutans serotype c and a strain of Streptococcus sobrinus serotype g) from the human oral cavity were subcultured one hundred times in brain heart infusion broth. Considerable changes were found in the virulence-related factors of mutans streptococci during repeated subculture. The results were summarized as follows. 1. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and radioimmunoassay showed that the amount of a cell-surface protein antigen with a molecular weight of 190, 000 (PAc) of S. mutans serotype c, which is considered to be important in the sucrose-independent cellular adherence, exhibited considerable changes after repeated subculture. Moreover, there was a correlation between the cell-surface hydrophobicity and the amount of PAc on the cell surface. On the other hand, the amount of a cell-surface protein antigen with a molecular weight of 210, 000 (PAg) of S. sobrinus serotype g was not influenced during repeated subculture, and the cell-surface hydrophobicity was relatively constant. In addition, changes in the expression of several cell-surface proteins and extracellular proteins other than the protein antigens were noticed after repeated subculture in S. mutans and S. sobrinus. 2. Changes in the glucan-synthesizing ability, which is known to be important in the sucrose-dependent cellular adherence, was also found after subculture in S. mutans and S. sobrinus. There was a correlation between the cell-associated 1N NaOH-soluble glucan-synthesizing ability and the in vitro sucrose-dependent cellular adherence ability. 3. Almost no change was observed in the abilities for acid production and cell growth. 4. The cariogenicity of S. mutans in hamsters was reduced after repeated subculture. It was suggested that the reduced cariogenicity might be ascribed to the changes of the PAc expression and the cell-associated 1N NaOH-soluble glucan-synthesizing ability.
- 1988-12-25