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Published on: December 19, 2020
Preparation and properties of type-specific M antigen isolated from a group A, type 1 hemolytic streptococcus
Abstract:
Type-specific M antigen was extracted by heating type 1 group A streptococci at pH 2 in a boiling water bath. The protein was then purified by digestion with a preparation of crystalline ribonuclease which was free of proteolytic activity. It was further purified by fractional precipitation with (NH(4))(2)SO(4). Elementary chemical analysis of the preparation thus obtained showed an absence of phosphorus and a sulfur content of 2.46 per cent. In the ultraviolet the maximum absorption was at a wave length of 276 mmicro and the minimum at 255 mmicro. In electrophoresis experiments the preparation showed a single peak in the pH range of 3 to 9, but considerable boundary spreading was observed. The type 1 M antigen was isoelectric at pH 5.3 in sodium acetate buffer of ionic strength 0.1. The serological reactivity of the protein isolated was typical of type 1 M antigen. This protein induced the formation in rabbits of type-specific precipitins and protective antibodies. The absorption of type 1 antibacterial serum with the purified M antigen removed both the protective antibodies and the type-specific precipitins from the serum.
Insights
Researchers purified type-specific M antigen from group A streptococci. This purified protein demonstrated serological reactivity, inducing protective antibodies and type-specific precipitins in rabbits.
Area of Science:
- Microbiology
- Immunology
- Biochemistry
Background:
- Group A streptococci (GAS) are significant human pathogens.
- M protein is a major virulence factor and a key target for type-specific immunity.
Purpose of the Study:
- To isolate and characterize the type-specific M antigen from type 1 group A streptococci.
- To confirm the serological reactivity and immunogenic properties of the purified M antigen.
Main Methods:
- Acid extraction and heat treatment of streptococci.
- Purification using ribonuclease digestion and fractional ammonium sulfate precipitation.
- Characterization by chemical analysis, UV spectroscopy, and electrophoresis.
- Immunization of rabbits and serological testing.
Main Results:
- A purified M antigen preparation was obtained, free of phosphorus and containing 2.46% sulfur.
- UV absorption showed maxima at 276 nm and minima at 255 nm.
- Electrophoresis revealed a single peak between pH 3-9, with an isoelectric point at pH 5.3.
- The purified antigen induced type-specific precipitins and protective antibodies in rabbits.
Conclusions:
- The isolated protein is the type-specific M antigen of type 1 group A streptococci.
- This M antigen is capable of eliciting protective and type-specific immune responses.
