DISTRIBUTION OF FIBRONECTIN-BINDING PROTEINS AMONG GROUP-A STREPTOCOCCI OF DIFFERENT M-TYPES

Binding of fibronectin by group A streptococci (GAS) promotes adherenc e to epithelial cells. The fibronectin-binding activity and the presen ce of prtF, a gene encoding a fibronectin-binding protein, were studie d among 109 strains. Fifty-six strains of 42 different M types possess ed prtF-related genes, and 89% of these strains bound fibronectin at h igh levels. The prtF-related genes varied in the number of repeats tha t constitute one of its two fibronectin-binding domains. Fifty-three s trains of 21 different M types lacked prtF. Thirty-nine of these (74%) , representing 13 different M types, bound fibronectin at very low lev els. However, 9 (17%), of 5 different M types, bound fibronectin at hi gh levels. The presence of prtF and the capacity to bind fibronectin c orrelated strongly with the M type of various strains of GAS. This cor relation may suggest the existence of a relationship between fibronect in binding and the pathogenic potential of GAS.