Lysis and lysogenization of groups A, C, and G streptococci by a transducing bacteriophage induced from a group G Streptococcus.

A temperate bacteriophage, designated GT-234, was isolated from a group G Streptococcus after ultraviolet irradiation. After several single-plaque passages in a group G indicator strain, this phage formed plaques in 3 of 14 group A strains, in 3 of 15 group C strains, and in 4 of 13 group G strains-but not in some representatives of several other serogroups. After propagation in each of the sensitive strains, the progeny from each was shown to be the same phage by (i) adsorption and plaque formation in each of the other groups, (ii) lysogenization in each of the other groups, (iii) high titers on infection of each serogroup, regardless of the group of propagating strain, and (iv) neutralization of infection in each of the other groups by antiserum against the phage propagated in group G. Phage GT-234 is serologically related to virulent group A phage A25, from which it is morphologically indistinguishable. Like A25, it is a transducing phage. Other studies showed that A25, as well as a group A temperate transducing phage (AT-298), could also infect strains of group C and G. These results indicate a need for reassessment of group specificity and phage receptors among streptococci of groups A, C, and G and raise possibilities for intergroup transduction.