THE ROLE OF HEMOLYSIN(S) IN THE PATHOGENESIS OF SERPULINA-HYODYSENTERIAE

Serpulina (Treponema) hyodysenteriae, an anaerobic beta hemolytic spir ochaete, is the etiologic agent of swine dysentery. Not much is known at present about the virulence factors of S. hyodysenteriae. However, the hemolysin production of this bacterium is generally accepted to be a virulence factor. To study the exact role of hemolysin production i n the pathogenesis of swine dysentery, the gene encoding a hemolysin, tly, was cloned and its nucleotide sequence determined. After inactiva tion of this gene, the virulence of a tly-minus mutant in mice was tes ted. The mutant had reduced hemolysis indicating that the tly-encoded hemolysin was not the only hemolysin produced by S. hyodysenteriae. Mi ce infected with the tly-minus mutant had fewer cecal lesions than mic e infected with the wild-type S. hyodysenteriae. It was concluded that the tly-encoded hemolysin might be an important virulence factor, but not the only one. Since it was demonstrated that spirochaetes can be transformed through. electroporation, this has made a genetic approach to elucidate the pathogenesis of spirochaetal infections possible.