Characteristics of transducing group A streptococcal bacteriophages A 5 and A 25

Summary The virulent, transducing, DNA-containing group A streptococcal bacteriophages A5 and A25 are 58 m in head size and have a flexible, noncontractile tail with a length of 180 m. The morphologic outline of the head is hexagonal. Treatment of the bacteriophages with potentially lethal ultraviolet radiation produced damages which were repairable by the Hcr⁺ streptococcal host strain K56, the host-cell reactivable sector being 0.9. These properties together with a demonstrable serological cross reaction show a close relationship between the two phage strains.