RIBOTYPING TO DIFFERENTIATE FUSOBACTERIUM-NECROPHORUM SUBSP NECROPHORUM AND F-NECROPHORUM SUBSP FUNDULIFORME ISOLATED FROM BOVINE RUMINAL CONTENTS AND LIVER-ABSCESSES

Differences in biological activities (hemagglutination, hemolytic, leu kotoxic, and virulence) and ribotypes between the two subspecies of Fu sobacterium necrophorum of bovine ruminal and liver abscess origins we re investigated. Hemagglutination activity was present in all hepatic, but only some ruminal, strains of fusobacterium necrophorum subsp. ne crophorum, Ruminal F. necrophorum subsp. necrophorun had low leukotoxi n titers yet was virulent in mice, Fusobacterium necrophorum subsp, fu nduliforme of hepatic or ruminal origin had no hemagglutination activi ty, had low hemolytic and leukotoxic activities, and was less virulent to mice. For ribotyping, chromosomal DNAs of 10 F. necrophorum subsp, necrophorum and 11 F. necrophorum subsp. funduliforme isolates were d igested with restriction endonucleases (EcoRI, EcoRV, SalI, PstI, and HaeIII) and examined by restriction fragment length polymorphisms afte r hybridizing with a digoxigenin-labeled cDNA probe transcribed from a mixture of 16 and 23S rRNAs from Escherichia coli. The most discrimin ating restriction endonuclease enzyme for ribotyping was EcoRI. The pr esence or absence of two distinct bands of 2.6 and 4.3 kb differentiat ed the two subspecies, Regardless of the origin, only F. necrophorum s ubsp, necrophorum, a virulent subspecies, had a ca, 2.6-kb band, where as F. necrophorum subsp, funduliforme, a less virulent subspecies, had a ca, 4.3-kb band, Ribotyping appears to be a useful technique to gen etically differentiate the two subspecies of F. necrophorum.