Integration of bacteriophage SP24 into the chromosome of group A streptococci.

The group A streptococcal bacteriophage SP24 contains a unique phage att site and integrates into a common chromosomal locus in two unrelated group A streptococcal strains, CS24 and CS112. Southern blot analysis suggested that the terminally redundant phage DNA recombines to form the unit-length genome observed in the prophage state. Phage DNA integration appears to be required for stable lysogen formation and conversion to the M+ state; however, the precise role of the bacteriophage and the relationship of phage integration to increased M protein synthesis are unclear.