DEVELOPMENT OF AN EXPERIMENTAL-MODEL ALLOWING DISCRIMINATION BETWEEN VIRULENT AND AVIRULENT ISOLATES OF SERPULINA (TREPONEMA) HYODYSENTERIAE

Variation in virulence among different strains of Serpulina hyodysente riae was studied by oral inoculation of specific pathogen free piglets and CD-1 mice. Piglets infected with serotype 2 reference strain B204 and an untypable field strain LHV-90-9-I had severe diarrhea tainted intermittently with mucus and fresh blood, The piglets inoculated with B169, B8044, B6933, and ACK300-8 reference strains representing serot ypes 3, 5, 6, and 7 respectively developed moderate diarrhea, However, reference strains B234 and A-1 of serotypes 1 and 4, respectively, fa iled to cause any diarrhea, None of the S. hyodysenteriae strains caus ed diarrhea in mice. The results indicate a great variation in virulen ce among strains of different serotypes of S. hyodysenteriae. Mice wer e less susceptible to infection with S. hyodysenteriae.