Characterization of M-Type-Specific Pilus Expression in Group A Streptococcus.

In addition to providing a typing mechanism for group A Streptococcus (GAS) isolates (T typing), cell surface pilus production impacts GAS virulence characteristics, including adherence and immune evasion. The pilus biosynthesis genes are located in the fibronectin- and collagen-binding T-antigen (FCT) region of the genome, and nine different FCT types, encoding more than 20 different T types, have been described. GAS isolates are not uniform in their degree or pattern of pilus expression, as highlighted by pilus production being thermoregulated in isolates that harbor the FCT-type FCT-3 (e.