Cross protection between an encapsulated strain ofStaphylococcus hyicusand encapsulated strains ofStaphylococcus aureus

摘要

Strain ST67P ofStaphylococcus hyicusgrew diffusely in regular serum‐soft agar. With the addition of rabbit antisera prepared withStaph. aureusstrains, Smith, NS58D or NS41D, capsular type A, B or C, respectively, the organisms converted to compact type growth. Mice immunized with heat‐killed vaccine of strain ST67P showed significant resistance against either homologous or heterologous strains, Smith, NS58D and NS41D. Passive protective activities in rabbit antisera prepared with strains Smith, NS58D and NS41D were absorbed out with either homologous cell surface polysaccharide fraction or cell surface polysaccharide fraction extracted from strain ST67P. Well‐defined large capsules were observed in ultra‐thin sections treated with rabbit antiserum prepared with homologous strain conjugated with ferritin. Also, the capsule surrounded by ferritin granules was shown in ultra‐thin sections treated with ferritin conjugated with antisera prepared with those heterologous strains although the capsular size was significantly smaller than those observed by homologous