Group A streptococcal phage T12 carries the structural gene for pyrogenic exotoxin type A.

The structural gene for group A streptococcal pyrogenic exotoxin (SPE) type A was cloned into E. coli. DNA fragments used for cloning the toxin gene were isolated from bacteriophage T12. Toxin, present in cell lysates of E. coli clones, immunoprecipitated with antisera raised against purified SPE type A and formed a line of identity with streptococcal-derived A toxin. The cloned toxin shared the following biological activities with streptococcal A toxin: Pyrogenicity; enhancement of host susceptibility to lethal endotoxin shock; nonspecific lymphocyte mitogenicity; and alteration of immunoglobulin production. The physical location of the toxin gene on the phage T12 genome was determined.