Serology of Listeria monocytogenes. I. Characteristics of the soluble hemolysin.

Girard, Kenneth F. (St. Margaret's Hospital, Boston, Mass.), Anthony J. Sbarra, and Wadi A. Bardawil. Serology of Listeria monocytogenes. I. Characteristics of the soluble hemolysin. J. Bacteriol. 85:349-355. 1963.-Our results clearly demonstrate that Listeria monocytogenes (strain 9-125) produces a soluble hemolysin. Such hemolysin is completely precipitated out of sterile culture filtrates by 60% saturation with ammonium sulfate at 5 C, and virtually all of the hemolytic activity resides in the so-called "euglobulin" fraction. The protein nature of this hemolysin is further indicated by its nondialyzable property, heat lability, susceptibility to proteolysis by trypsin, and antigenicity in the full sense. Paper electrophoresis indicates that the isolated active fraction migrates as a gamma-type globulin. A procedure for determining Listeria antihemolysin levels in sera adapted from a method commonly employed for quantitating antistreptolysin O is described. The relative value of anti-Listeria hemolysin titration as a possible serological aid in diagnosis remains to be determined and is presently under investigation.