Which of the following factor is mainly respon-sible for virulence in Streptococcus :

M Protein It is major virulence factor of group A Strep. pyogenes. It is hair like projection of cell wall. It is of 80 types (basis of Griffith classification) so immunity is type specific. M protein is also found in Group G streptococci. Remember : Carbohydrate is used as the basis of Lancefields classification. Streptokinase or fibrolysin and streptodornase or DNAse liquefy pus so used in enzymatic debridement