Evidence for two distinct classes of streptococcal M protein and their relationship to rheumatic fever.

Abstract

The antigenic relatedness of surface-exposed portions of M protein molecules derived from group A streptococcal isolates representing more than 50 distinct serotypes was examined. The data indicate that the majority of serotypes fall into two major classes. Class I M protein molecules share a surface-exposed, antigenic domain comprising the C repeat region defined for M6 protein. The C repeat region of M6 protein is located adjacent to the COOH-terminal side of the pepsin-susceptible site. In contrast, Class I M proteins display considerably less antigenic relatedness to the B repeat region of M6 protein, which lies immediately NH2-terminal to the pepsin site. Surface-exposed portions of Class II M proteins lack antigenic epitopes that define the Class I molecules. Studies in the 1970s demonstrated that M protein serotypes can be divided into two groups based on both immunoreactivity directed to an unknown surface antigen (termed M-associated protein) and production of serum opacity factor. These two groups closely parallel our current definition of Class I and Class II serotypes. Both classes retain the antiphagocytic property characteristic of M protein, and Class II M proteins share some immunodeterminants with Class I M proteins, although the shared determinants do not appear to be exposed on the streptococcal surface. Nearly all streptococcal serotypes associated with outbreaks of acute rheumatic fever express M protein of a Class I serotype. Thus, the surface-exposed, conserved C repeat domain of Class I serotypes may be a virulence determinant for rheumatic fever.

• Authors: D Bessen, K F Jones, V A Fischetti
• Journal: The Journal of experimental medicine (J Exp Med) Vol. 169 Issue 1 Pg. 269-83 (Jan 01 1989) ISSN: 0022-1007 [Print] United States
• PMID: 2642529 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Antigens, Bacterial
• Antigens, Surface
• Bacterial Outer Membrane Proteins
• Bacterial Proteins
• Carrier Proteins
• Oligopeptides
• opacity factor
• streptococcal M protein
• Peptide Hydrolases

Topics

• Antigens, Bacterial (analysis, classification)
• Antigens, Surface (analysis, classification)
• Bacterial Outer Membrane Proteins
• Bacterial Proteins (classification, immunology, ultrastructure)
• Blotting, Western
• Carrier Proteins
• Oligopeptides (immunology)
• Peptide Hydrolases (biosynthesis)
• Rheumatic Fever (microbiology)
• Serotyping
• Streptococcus pyogenes (classification, pathogenicity)