M protein (Streptococcus)
M protein is a virulence factor that can be produced by certain species of Streptococcus.[1] M protein is strongly anti-phagocytic and is a major virulence factor. It binds to serum factor H, destroying C3 convertase and preventing opsonization by C3b. However plasma B cells can generate antibodies against M protein which will help in opsonization and further off destruction of the microorganism by the macrophages and neutrophilis. Cross-reactivity of anti-M protein antibodies with heart muscle is the basis for rheumatic fever.
It was originally identified by Rebecca Lancefield,[2] who also formulated the Lancefield classification system for Streptococcal bacteria. Bacteria like S. pyogenes which possess M protein are classified in group A of the Lancefield system.
References
- ^ Chanter N, Talbot NC, Newton JR, Hewson D, Verheyen K (2000). "Streptococcus equi with truncated M-proteins isolated from outwardly healthy horses". Microbiology (Reading, England). 146. ( Pt 6): 1361–9. PMID 10846214.
{{cite journal}}: Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ "Streptococcal M protein: molecular design and biological behavior". Retrieved 2009-06-21.
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