Unspecific binding of group B streptococcal cocytolysin (CAMP factor) to immunoglobulins and its possible role in pathogenicity.
The protein B of group B streptococci can bind in a nonimmune reaction to Ig of the IgG and IgM classes of various mammalian species (i.e., human, mouse, rabbit, and bovine). Protein B binding involves the Fc parts of both IgG and IgM molecules. Monoclonal or polyclonal IgG or IgM and the IgM-FC5 mu fragment of human myeloma protein combined with the protein B thereby inhibiting protein B-induced hemolysis in the CAMP reaction. The protein B/Ig complex can be dissociated with 1% Triton or guanidine-HCl (6 M). Mice infected intraperitoneally with sublethal doses of group B streptococci (GBS) and that received seven repeated intravenous injections of highly purified protein B during the first 9 h of infection developed fatal septicemia within 24 h with colony counts of up to 10(8) CFU/ml in the blood. Animals treated in the same way with either PBS or trypsinized protein B recovered. The protein B itself was not pathogenic when injected into healthy mice. Tissue sections of liver or spleen from mice infected with a lethal dose of GBS revealed the presence of protein B together with large numbers of cocci when stained by the peroxidase method using specific antibodies raised against purified protein B in the rabbit.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001426:Bacterial Proteins / Q000032:analysis / Q000276:immunology*; D001666:Binding Sites, Antibody; D006460:Hemolysin Proteins; D006651:Histocytochemistry; D007124:Immunoenzyme Techniques; D007141:Immunoglobulin Fc Fragments / Q000378:metabolism; D007074:Immunoglobulin G / Q000378:metabolism*; D007075:Immunoglobulin M / Q000378:metabolism*; D008099:Liver / Q000032:analysis / Q000382:microbiology; D008297:Male; D051379:Mice; D018805:Sepsis / Q000276:immunology* / Q000382:microbiology; D013154:Spleen / Q000032:analysis / Q000382:microbiology; D013290:Streptococcal Infections / Q000276:immunology* / Q000382:microbiology; D013292:Streptococcus agalactiae / Q000302:isolation & purification
D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; C039092:CAMP protein, Streptococcus; D006460:Hemolysin Proteins; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D007075:Immunoglobulin M