Biological properties of alpha-toxin mutants of Staphylococcus aureus.

McClatchy, J. K. (The University of Texas Southwestern Medical School, Dallas), and E. D. Rosenblum. Biological properties of alpha-toxin mutants of Staphylococcus aureus. J. Bacteriol. 92:575-579. 1966.-Twenty nonhemolytic mutants of Staphylococcus aureus were isolated after treatment of a hemolytic strain with ultraviolet light or nitrous acid. Thirteen strains isolated were completely lacking in the synthesis of alpha toxin or immunologically related proteins, presumably the result of a single mutational event. Although the strains were nonhemolytic on rabbit blood-agar plates, six of them retained the dermonecrotic and lethal activities usually associated with staphylococcal alpha toxin, as well as slight hemolytic activity for rabbit erythrocyte suspensions. The active mutants and one inactive mutant produced a protein that reacted immunologically with antibody to alpha toxin. Mutations which alter the alpha toxin molecule can effect the lethal, dermonecrotic, and hemolytic activities separately or in varying ratios.