[Characteristics of the soluble antigens of bifidobacteria].

The immunological study of aqueous buffer extracts obtained from 45 strains of bifidobacteria belonging to the species B. bifidum, B. longum, B. adducens, B. breve, B. infantis and B. parvulorum was made. This study revealed 3 levels of the immunological specificity of soluble bifidobacterial proteins: common to the genus Bifidobacterium, common to a limited number of strains belonging to one or several species of bifidobacteria and strain-specific.