Protection against dental caries

Claim 1

A process for producing an antigen preparation, for use in the reduction or prevention of dental caries, from bacteria of the group Streptococcus mutans genetic group I, the preparation being substantially free from any heart cross reactive antigens derivable from Streptococcus mutans, wherein the process comprises growing bacteria of the group Streptococcus mutans genetic group I in a culture medium to produce a cell culture, removing at least the cell walls from the cell culture to leave a protein solution and separating the antigen preparation from the protein solution by a method of separation which comprises contacting the protein solution with immobilized antibody, washing unwanted materials from the immobilized antibody under such conditions that the antigen preparation is retained on the immobilized antibody and eluting the antigen preparation from the immobilized antibody under such conditions that the antibody remains in an immobilized state and the antigen preparation retains its antigenicity, wherein the immobilized antibody has a specificity for one or more antigenic proteins which have the following properties: they (a) are present on the cell walls of strains of Streptococcus mutans genetic group I; (b) are destroyed or extracted by treatment of said cell walls with boiling aqueous sodium dodecyl sulphate (SDS) solution (10 gm per liter) for 10 minutes but remain associated with said cell walls after treatment of the walls with aqueous SDS solution (10 gm per liter) at 15° C.; (c) have a molecular weight of 70,000±5,000 by SDS-polyacrylamide gel electrophoresis (SDS-PAGE); (d) are destroyed by proteolytic enzyme; (e) have an isoelectric point of 4.45±0.24; and (f) do not cross react with heart tissue.