Identification of non-immunoglobulin A-Fc-binding forms and low-molecular-weight secreted forms of the group B streptococcal beta antigen (original) (raw)
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Infection and immunity, 1990
We have characterized the immunoglobulin A (IgA)-Fc-binding properties and beta-antigen expression of several strains of group B streptococci by using ultrastructural immunocytochemistry. Colloidal gold-labeled tracers were used with intact and sectioned bacteria in order to gain information regarding the location and distribution of cell surface and cytoplasmic IgA-Fc-binding molecules and beta antigen. Colloidal gold (5- or 15-nm particles) was conjugated to IgA to characterize IgA-binding properties and to IgG to test for IgG binding. Rabbit anti-beta antiserum was reacted with the bacteria and then with protein G labeled with 15-nm colloidal gold particles. A double-labeling technique was used for simultaneous localization of IgA-Fc- and anti-beta-antibody-binding properties on sectioned bacteria. The data corroborated previous results which indicated that (i) IgA-Fc-binding and IgA-Fc-nonbinding forms of beta antigen can be secreted by strains which do not express beta antigen ...
The Journal of Immunology
A number of group A streptococcal isolates have been compared for their nonimmune reactivity with each human IgG subclass, and rabbit, pig, or horse IgG. The results obtained demonstrate considerable heterogeneity in the expression of type II IgG-binding proteins among and within group A isolates. Extraction and analysis of type II IgG-binding proteins from selected strains demonstrate the existence of five functionally distinct IgG-binding proteins. The type IIo IgG binding protein displayed the greatest range of reactivities, binding to all four human IgG subclasses, and rabbit, pig, and horse IgG. A variant of this protein, designated type II'o, bound all four human subclasses and rabbit IgG, but failed to react with pig or horse IgG. A type IIa protein was recovered from certain group A strains which bound human IgG1, IgG2, IgG4, as well as reacting with rabbit, pig, and horse IgG. A functionally related type IIc activity that displayed all of the reactivities of the type II...
Journal of bacteriology, 1995
We previously reported that group D streptococci exhibited immunoglobulin G (IgG)-binding activity and that a 52-kDa IgG-binding protein was present in all Streptococcus suis strains examined (B. Serhir, R. Higgins, B. Foiry, and M. Jacques, J. Gen. Microbiol. 139:2953-2958, 1993). The objective of the present study was to purify and characterize this protein. Pig IgG were immobilized through their Fab fragments to ECH-Sepharose 4B, and the protein was purified by affinity chromatography. Electron microscopy observations of the purified material showed filamentous structures with a diameter of approximately 4 nm; these structures were not observed when the material was treated with either urea or ethanolamine. Electrophoretic and Western immunoblot analyses showed that the 52-kDa protein constituted the bulk of the recovered material. This protein was stained with either Coomassie brilliant blue or silver nitrate; it reacted with a large variety of mammalian IgG, human IgG (Fc) frag...
Detection of immunoglobulin-G-binding proteins in Streptococcus suis
Journal of general microbiology, 1993
This study was undertaken to search for the presence of immunoglobulin G (IgG)-binding proteins in Streptococcus suis, an important swine pathogen. Whole bacterial cells were incubated with human or pig IgG conjugated to gold particles and examined by transmission electron microscopy. Cells of some S. suis strains were labelled as were cells of the positive control strain, Staphylococcus aureus Cowan I. Binding of pig and human IgG to five different bacterial species of group D streptococci, to reference strains representing the 29 capsular types of S. suis, and to 12 S. suis capsular type 2 strains was then examined using Western blotting. All strains interacted with pig and human IgG, although the binding profiles were slightly different. A 52 kDa protein was observed in all capsular types of S. suis. This protein, absent in other group D streptococcal species, was observed in all capsular type 2 isolates originating from diseased or clinically healthy pigs, and was shown to bind ...
Infection and Immunity, 1993
Expression of immunoglobulin G (IgG)-binding proteins on group A streptococcus strain 64 was monitored on bacteria subjected to sequential passage in human blood. After approximately 10 cycles through human blood, strain 64 demonstrated enhanced levels of IgG-binding protein, including the expression of a type IIa binding molecule with an M(r) of approximately 47,000 present only at very low levels on the parent isolate. Changes in the expression of IgG-binding proteins after passage in human blood were similar to those observed when the same organism was passaged sequentially intraperitoneally in mice. Strain 64, passaged in human blood 23 times, was found to be more virulent than the parent isolate when used to infect mice either intraperitoneally or in a skin air sac. These findings suggest that the expression of IgG-binding proteins may be a common response of group A organisms to pressures exerted by distinct host defense mechanisms.
Identification of the site on IgG Fc for interaction with streptococci of groups A, C and G
Immunology, 1987
The interaction between living groups A, C and G streptococci and IgG Fc was studied using human IgG, IgG Fc and IgG Fc-intermediate (Fci) fragments, chemically modified human IgG and fragment D of staphylococcal protein A (SPA). Diethylpyrocarbonate modification of His or N-acetylimidazole modification of Tyr of human IgG resulted in the loss of its capacity to inhibit the binding of radiolabelled human IgG Fc to the group A streptococci types M1 and M55, and to the group C strain SC-1, indicating that the amino acids His and Tyr are involved in the binding. Lys seems not to participate in the binding of IgG to these bacteria, however, since reductive methylation of Lys did not reduce its inhibitory capacity. Fragment D of SPA also inhibited the binding of radiolabelled human IgG Fc to strains M1, M55 and SC-1. We have previously shown that these bacteria do not bind to IgG fragments consisting of only the C gamma 2 or C gamma 3 domains. On the basis of these results, and the known...
Identification of a unique receptor on a group A streptococcus for the Fc region of human IgG3
The Journal of Immunology
Receptors that bind to the Fc region of all four human IgG subclasses have been described on a number of strains of group A streptococci. In this study, we have demonstrated that these immunoglobulin binding properties are mediated by two distinct Fc receptors. The first receptor, with a Mr of approximately 56,000, binds to human IgG1, IgG2, and IgG4, but not to IgG3. A second receptor, with a Mr of approximately 38,000, binds exclusively to human immunoglobulins of the IgG3 subclass.
1994
Analysis of group A streptococcal immunoglobulin G (IgG)-binding protein reactivity with different human IgG3-myeloma proteins provided evidence for at least two functional forms of these molecules. Representative IgG3-binding molecules were isolated, biotinylated, and used as tracers in competitive binding assays. Cross-inhibition studies demonstrated the existence of two distinct patterns of IgG3-binding activity. Proteins of one form could be inhibited from binding to an IgG3-myeloma protein by streptococcal protein G while binding of the second form was not inhibited. These studies further underscore the extent of heterogeneity among immunoglobulin-binding proteins expressed by group A streptococci.
Detection of receptors for the Fc region of IgG on streptococci
Journal of Immunological Methods, 1983
A semi-quantitative absorption test to measure Fc-reactive proteins on the surface of streptococci is described. The ability of bacteria to remove intact IgG in the presence of an equimolar amount of F(ab')2 fragments was used to identify streptococci with Fc-reactive proteins on their surface. This method was found to be more objective, reproducible and quantitative than the hemagglutination and t251-1abeled IgG binding methods currently in use. Methods for detection of secreted Fc-reactive materials with protein A-like reactivity are also described.