GROUP-A STREPTOCOCCAL VIR TYPES ARE M-PROTEIN GENE (EMM) SEQUENCE TYPE-SPECIFIC

The M-protein genes (emm genes) of 103 separate impetiginous Streptoco ccus pyogenes isolates were sequenced and the sequence types were comp ared to the types obtained by Vir typing, Vir typing is based on restr iction fragment length polymorphism (RFLP) analysis of a 4- to 7-kb pa thogenicity island encoding emm and other virulence genes, By using bo th Haem and HinfI to generate RFLP profiles, complete concordance betw een Vir type and emm sequence type was found, Comparison of the emm se quences with those in GenBank revealed new sequence types sharing less than 90% identity with known types, Diversity in the emm sequence was generated by corrected frameshift mutations, point mutations, and sma ll in-frame mutations.