Systematic Veterinary Bacteriology and Mycology

Antigenicity

ANTIGENECITY

• The hyaluronic acid capsule of S. pyogenes inhibits phagocyotosis.
• The cell wall is composed of an outer layer of fimbria containing proteins and lipoteichoic acid, a middle layer of group specific carbohydrate and an inner layer of peptidoglycan.
• The Cell wall polysaccharide has been shown to have a toxic effect on connective tissue in experimental animals.
• The peptidoglycan is responsible for cell wall rigidity. Several protein antigens have been identified in the cell wall (M, T and R).
• They are responsible for type specificity in S.pyogenes. Among these the M protein acts as a virulence factor by inhibiting phagocytosis.
• Hair-like pili project through the capsule of group A streptococci.
• The pili consist partly of M protein and are covered with lipoteichoic acid which is important in the attachment of streptococci to epithelial cells.