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Factors affecting the chain length of group A streptococci. II. Quantative M-anti-M relationships in the long chain
Abstract:
Minute amounts of M protein were detected in culture supernates of virulent Group A streptococci by type-specific inhibition of the long chain and the bactericidal tests for anti-M antibody. The amount of M protein that was detected by the inhibition of these biological systems was less than could be demonstrated by precipitation tests. All strains of streptococci rich in M protein which were studied formed long chains when grown in sufficient concentrations of anti-M antibody. Very low concentrations of anti-M antibody escaped detection by the long chain test when strains of excessive M protein content were employed. Under such conditions the bactericidal test detected anti-M antibody more sensitively than the long chain test owing to the smaller inoculum employed in the former method. The scission of streptococcal chains may be inhibited by union of antibodies with surface antigens other than M protein. Long chains were formed when M-negative, R-positive strains were grown in sera containing anti-R antibody.
Insights
Minute M protein in Group A streptococci was detected using antibody inhibition tests. The bactericidal test proved more sensitive than the long chain test for detecting anti-M antibody in certain strains.
Area of Science:
- Microbiology
- Immunology
- Bacteriology
Background:
- Group A streptococci possess M protein, a key virulence factor.
- Anti-M antibody is crucial for host defense against these bacteria.
- Detecting M protein and anti-M antibody is important for diagnosis and research.
Purpose of the Study:
- To compare the sensitivity of M protein detection methods.
- To evaluate the efficacy of long chain and bactericidal tests for anti-M antibody detection.
- To investigate factors influencing antibody detection in Group A streptococci.
Main Methods:
- Detection of M protein in culture supernates of Group A streptococci.
- Type-specific inhibition assays using anti-M antibody.
- Comparison of long chain formation and bactericidal tests.
- Assessment of streptococcal strains with varying M protein content.
Main Results:
- Minute M protein amounts were detected by antibody inhibition, less than by precipitation.
- Strains rich in M protein formed long chains in anti-M antibody.
- The bactericidal test was more sensitive than the long chain test for low anti-M antibody concentrations.
- Antibody binding to non-M surface antigens can inhibit chain scission.
Conclusions:
- Antibody inhibition tests can detect low levels of M protein.
- The bactericidal test offers higher sensitivity for anti-M antibody detection under specific conditions.
- Understanding these detection methods aids in studying streptococcal pathogenesis and immunity.
