Abstract
Viable cells of Fusobacterium necrophorum biovar A were inoculated into the ruminal vein of cattle. Two cattle inoculated with more than 4.4×108 viable cells died within 2 days after inoculation. Disseminated necrotic foci were observed in their liver. When 2.8×106 to 1.4×108 viable cells were inoculated into 7 cattle, these cattle manifested no sickness clinically, with the exception of one calf which died. By autopsy, however, hepatic abscesses were recognized in these cattle 9 to 21 days after inoculation. In addition, lung abscesses were also formed in 3 calves of 2 months old. F. necrophorum was recovered from the hepatic abscesses and lung abscesses in viable counts ranging from 106 to 109 per gram. The organism were also isolated from the normal position of the liver, the hepatic lymph node and other organs in some cattle. But the viable counts were lower than those of the abscesses. In two calves, Corynebacterium pyogenes was isolated from the hepatic abscess and lymph node. On the contrary, no hepatic abscess nor necrotic focus was formed in a calf when 1.2×109 viable cells were inoculated into the jugular vein. The precipitating antibody was demonstrated in all cattle having hepatic abscesses by the immunodiffusion test with the concentrated culture supernatant of F. necrophorum. The maximum antibody titer in the cattle ranged from 16 to 128.
