ARS | Publication request: EVALUATION OF THE VIRULENCE OF RHEA S. HYODYSENTERIAE STRAINS FOR SWINE

Submitted to: International Virtual Conference on Infectious Diseases of Animals
Publication Type: Abstract Only
Publication Acceptance Date: May 2, 1997
Publication Date: N/A

Technical Abstract: Serpulina hyodysenteriae (S. hyo) is the etiologic agent of swine dysentery. Although the natural host range of this spirochete is generally considered limited to swine, recent findings suggest that S. hyo has the potential to cause intestinal disease in other animals. S. hyo strains were isolated from rheas with a severe necrotizing typhlocolitis. In these experiments, we evaluated whether S. hyo strains R1 and R358, isolated from rheas were virulent for swine. The rheas had died due to severe typhlocolitis. In 2 experiments, postweaning piglets were inoculated intragastrically. On 2 consecutive days, each experimental group animal received 100 ml of BHIS broth containing 10**10-6 x 10*810 cfu of a rhea S. hyo strain. Animals in control groups received either 100 ml of sterile BHIS broth or cultures of S. hyo B204, a strain virulent for swine. Swine given S. hyo B204 cells first appeared ill within 24-36 hr after the second inoculation and all (12/12) of the B204-infected swine showed clinical signs of swine dysentery. Nine of 12 animals had significant weight loss and developed intestinal mucosal lesions consistent with swine dysentery. By contrast, none of the swine given rhea strain R1 (14 animals), strain R358 (6 animals) or sterile culture broth developed dysentery or displayed histopathological signs of intestinal damage. Only one animal (R1 group) had detectable S. hyo cells in its feces and only at 24 hr after the challenge inoculation. These results indicate that S. hyodysenteriae strains R1 and R358 are avirulent for swine. Comparisons of the biochemical and genetic properties between these rhea strains and swine strains could lead to the identification of characteristics essential for the virulence of S. hyo in swine.