Presence of Hemolysin in Cultures of Pathogenic Leptospires

Abstract

SummaryA chance observation of the hemolysis of sheep red blood cells by a culture of leptospires was investigated. Studies were conducted on a newly disclosed serotype strain, isolated in Malaya and designated as Leptospira hemolyticus. The presence of a soluble non-dialysable, thermolabile, oxygen-stable hemolysin in the supernatant fluid of cultures was demonstrated. The optimum temperature for hemolytic activity was 37°C. At lower temperatures the activity of hemolysin progressively decreased. The hemolytic activity against sheep RBC occurred after a prolonged induction period. This phenomenon as well as the atypical kinetic activity of varying concentrations of hemolysin preparations were attributed to the inhibitory activity of the rabbit serum present in culture supernatants. The production of hemolysin was not a generic characteristic but was restricted to specific serotype strains. Hemolytic activity of L. hemolyticus was manifested against sheep, cow, goat RBC, but not against RBC of eleven other species screened. The antigenicity of this hemolysin could not be demonstrated. In actively growing cultures, maximum amounts of hemolysin were produced 1 to 3 days following optimum growth. The presence of a soluble hemolysin in specific serotype strains may figure significantly in explaining the pathogenicity of leptospiral infections.