Homology between surface protein antigen genes of Streptococcus sobrinus and Streptococcus mutans

Abstract
The structural gene (pag gene) for a 210 kDa protein antigen of Streptococcus sobrinus serotype g was cloned and compared with that (pac gene) of a 190 kDa protein antigen of Streptococcus mutans serotype c. Immunodiffusion analysis revealed that the product of the pag gene immunologically cross‐reacted with that of the pac gene. Southern blot and nucleotide sequence analyses revealed that a significant homology existed between the middle regions of the two structural genes.