| 摘要 |
An antigenic protein, termed antigen A, present on the cell walls and in cultures of Streptococcus mutans, especially genetic group I (serotypes c, e and f) is separated from other antigenic proteins, notably those which cross-react with heart tissue, to give an antigenic preparation which may be used as a vaccine or to raise antibodies for use in protecting against dental caries. Antigen A is one of two major antigenic proteins remaining on cell walls of S. mutans genetic group I after extraction with a boiling 10 g/l liter aqueous solution of sodium dodecyl sulphate for 20 minutes. It has a molecular weight of about 29,000, an isoelectric point of 4.1 to 4.5. Its amino-acid analysis is also given. The antigen also occurs in the culture filtrate and/or cell extract and may be readily purified from these sources by, for example fractional ammonium sulphate precipitation and/or affinity chromatography on immobilized antibody. |
