In vitro direct haemagglutination by Corynebacterium ovis exotoxin.

Haemagglutinating activity of toxigenic Corynebacterium ovis culture supernatants was estimated by titration in phosphate buffered saline diluent against sheep erythrocytes. The haemagglutination titre was closely related to the haemolysis and rabbit dermonecrosis titres of culture supernatants and to the toxigenicity of different C ovis strains. The substance responsible for haemagglutination was diffusible and its concentration was unrelated to cell yield in cultures. Corresponding inactivation of all three activities by antitoxin, toxoid formation with formalin, heat and Seitz filtration suggested that haemagglutination is another activity of C ovis exotoxin.