Haemolytic and adhesive properties of Treponema hyodysenteriae
Optimal conditions for preparation and storage of haemolysin
were determined using spirochaetes harvested from rabbit
serum broth. Haemolysin was purified by fractionation on
Whatman DEAE Cellulose and Sephadex G100, purity being assessed
by SDS-PAGE. The molecular weight of the haemolysin was
estimated by gel filtration to be 19,000 daltons although
analysis on SDS-PAGE suggested that the molecular weight
of haemolysin dissociated from the RNA-core carrier was
much lower. The purified haemolysin was not antigenic.
The unpurified haemolysin caused lysis of several species
of erythrocyte and was cytotoxic towards a range of cell
monolayers, embryo bovine lung fibroblasts being the most
sensitive. The cytotoxic activity of the haemolysin was
quantified using a
release assay. Of the porcine
inflammatory cells tested, lymphocytes were the most sensitive.
After purification the preparation was haemolytic and leucotoxic
but was less cytotoxic.
Lower concentrations of haemolysin were produced by
an avirulent strain of T. hyody4enteniae than from the virulent
strain and it was not toxic for embryo bovine lung fibroblasts.
No toxic effect of haemolysin from virulent strains
of T. hyody4entetiae was demonstrated either by inoculation
of high concentrations into ligated colonic loops in pigs
or by intragastric inoculation of CFI mice.
The treponemal haemolysin is similar to Streptolysin
S in the requirement for a carrier molecule to demonstrate invino haemol. ysis, and with respect to molecular weight, lack
of antigenicity, cytotoxic activity and the effect on lymphocytes.
When T. hyodyzente4iaew as incubated with excised colonic
tissue slices and inoculated into ligated colonic loops
in pigs, spirochaetes associated with the mucus rather than
attaching to the colonic epithelium. Within 2 hours, spirochaetes
were observed in the bottom of crypts suggested that a chemotactic
mechanism may be more important than attachment in enabling
T. hyodyzenten£ae to establish in the colon.