Experimental Treponema hyodysenteriae infection of mice.

Factors such as strain, fasting period, sex and age of the animals, and challenge dose were examined for their effects on the development of infection with Treponema hyodysenteriae in mice. Among mice tested, Ta:CF#1 mice were the most susceptible to the infection. Ta:CF#1 mice developed gross cecal lesions by a single oral dose ranging 10(2)-10(7) colony-forming units of T. hyodysenteriae without preinoculation fast. Oral challenge with 10(7) colony-forming units of the treponeme resulted in the development of gross lesions in all the mice at day 10. The number of T. hyodysenteriae in the feces and cecum of the mice reached the highest level at day 7 and 10, respectively; the levels lasted until day 21, the termination of the experiment. Macroscopic, microscopic and scanning electron microscopic findings of the lesions were similar to those of swine dysentery. These studies indicate that the Ta:CF#1 mice may be used as an excellent in vivo model system for swine dysentery.