Inactivation of a Serpula (Treponema) hyodysenteriae hemolysin gene by homologous recombination: Importance of this hemolysin in pathogenesis of S. hyodysenteriae in mice

Abstract

The role of Serpula hyodysenteriae hemolysin in the pathogenesis of swine dysentery was studied. The inactivation of a gene, tly, encoding a hemolysin, and the virulence of a tly − mutant in mice is reported. We obtained chromosomal integration of the distrupted tly gene via homologous recombination in a S. hyodysenteriae wild-type strain following electroporation. A plasmid construct, in which the tly gene was disrupted by a kanamycin-resistance gene, was used for the electroporation. The mutants obtained had reduced hemolysis indicating that the tly encoded hemolysin is not the only hemolysin produced by S. hyodysenteriae. Mice infected with the tly − mutant had fewer cecal lesions than mice infected with the wild-type S. hyodysenteriae. From these results it was concluded that the tly encoded hemolysin may be an important virulence factor, but not the only one. It was demonstrated that gene transfer to spirochaetes can be achieved through electroporation.