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Binding of streptococcal antigens to muscle tissue in vitro
Abstract:
Antigens extracted from cells of Streptococcus pyogenes T6 and Streptococcus mutans strains AHT, BHT, 10449, OMZ175, and K1R adsorbed to the sarcolemmal sheath of cardiac muscle cells in vitro. Similar preparations from S. salivarius, S. sanguis, Staphylococcus aureus, and Lactobacillus casei had weak or negligible tissue-binding activity. Tissue-bound bacterial antigens were detected with homologous rabbit antisera with both indirect immunofluorescence tests and an indirect radioimmunoassay. Serological cross-reactivity was observed between the tissue-binding factors of S. pyogenes and S. mutans cells but not between the bacteria and muscle tissue. In a comparative study of extraction procedures, the greatest yield of tissue-binding factors was obtained from group A streptococci by cell disruption in buffer at 4 degrees C. Hot aqueous phenol and hot water extracts were inactive. Antibodies specific for the tissue-binding factor(s) were readily adsorbed from rabbit anti-S. pyogenes serum by a preparation of isolated cytoplasmic membranes but not by a suspension of cell wall fragments. The heart-binding component of S. pyogenes cell extracts was inactivated by protease digestion and heat treatment and to a lesser extent by periodic acid oxidation. The capacity of heart cell components to adsorb streptococcal antigens was reduced by protease treatment but not by the action of neuraminidase, hyaluronidase, organic solvents, or detergents.
Insights
Streptococcus pyogenes and Streptococcus mutans antigens bind to heart muscle cells, identified using immunofluorescence and radioimmunoassay. These tissue-binding factors are primarily located in the cytoplasmic membranes and are sensitive to protease digestion.
Area of Science:
- Microbiology
- Immunology
- Cardiology
Background:
- Bacterial adherence to host tissues is a key factor in pathogenesis.
- Certain Streptococcus species, including Streptococcus pyogenes and Streptococcus mutans, have been implicated in cardiac conditions.
Purpose of the Study:
- To investigate the ability of antigens from Streptococcus pyogenes and Streptococcus mutans to bind to cardiac muscle cells in vitro.
- To characterize the nature and location of these tissue-binding bacterial antigens.
Main Methods:
- Extraction of antigens from various bacterial strains.
- Incubation of bacterial extracts with isolated cardiac muscle cells.
- Detection of tissue-bound antigens using indirect immunofluorescence and indirect radioimmunoassay.
- Characterization of antigen properties through protease digestion, heat treatment, and oxidation.
Main Results:
- Antigens from Streptococcus pyogenes and Streptococcus mutans demonstrated significant binding to cardiac muscle cell sarcolemma.
- Bacterial antigens from other species showed weak or negligible binding.
- Tissue-binding factors were primarily associated with cytoplasmic membranes, not cell walls.
- The heart-binding component was inactivated by protease and heat, suggesting a proteinaceous nature.
Conclusions:
- Specific antigens from Streptococcus pyogenes and Streptococcus mutans possess the ability to bind to cardiac muscle cells.
- This binding is mediated by protein components located in the bacterial cytoplasmic membranes.
- The findings suggest a potential mechanism for cardiac tissue involvement by these bacteria.