Biological and biochemical characteristics of Fusobacterium necrophorum leukocidin.

The production of a leukocidal exotoxin by 18-hour dialysis cultures of Fusobacterium necrophorum was detected in vitro by a cytotoxicity assay, using bovine leukocytes isolated from peripheral blood. Biological characteristics were determined while maximizing the in vitro assay. Biochemical characteristics of heat stability and stability to degradative enzymes were investigated and indicated that the leukocidin is protein in nature. The characteristics indicate that this leukocidin is different from previous descriptions in the literature of the characteristics of a leukotoxin produced by F necrophorum.