Hemolytic Activity of Moraxella bovis

Abstract

The hemolytic activity of Moraxella bovis was investigated. It reached a maximum level in the initial stage of the logarithmic phase. This level was maintained for at least 120 hours during which the shaken culture of M. bovis in trypticase soy broth had been examined sequentially. Hemolysin was inseparable from the bacillary body, because after filtration through 0.45 μm Millipore filter or centrifugation at 8, 000 rpm, no hemolytic activity was proved in the filtrate or supernatant. No difference was demonstrated in the susceptibility of erythrocytes to this hemolysin among several species of animals. The hemolysin of M. bovis was activated by Ca⁺⁺, but not by any reducing agent, and destroyed by heat, formalin and trypsin. In seven of 8 sera collected from clinically infected calves, a distinct increase of antihemolytic antibody titer was proved. Some discussion was made on the findings mentioned above.