Identification of group A type 1 streptococcal M protein gene by a non-radioactive oligonucleotide detection method.

An oligonucleotide probe of 30 nucleotides length has been constructed, spanning the codons of amino acids 2 to 11 of the mature M1 protein of group A streptococci (Streptococcus pyogenes). It was labeled with digoxigenin-dUTP and visualized after hybridization with an anti-digoxigenin-antibody/alkaline phosphatase conjugate. It definitely detected the emm1 gene in dot-blotted 20-micrograms amounts of total nucleoid acid extracts. When tested with 27 type M1 group A streptococci of several epidemiologically unrelated outbreaks and 24 non-M1 strains, its sensitivity and specificity of detection reached 100% even at a hybridization temperature 35 degrees C below the calculated Tm. A detailed protocol for the construction and use of this oligonucleotide probe is given.