Analysis of lipopolysaccharide antigens of Treponema hyodysenteriae

Lipopolysaccharide (LPS) extracts obtained from Treponema hyodysenteriae of serogroups A, B, D and E, and from T. innocens were examined by SDS-polyacrylamide gel electrophoresis (SDS-PAGE), silver-staining, and immunoblotting with hyperimmune rabbit sera. All organisms possessed multiple LPS bands, but their position and number differed. Immunoblotting of LPS with grouping sera identified three or four major antigenic LPS components in the 10-42 kDa range in all organisms: these components were largely specific to each type-organism of a serogroup, and presumably represented group antigens. Although some minor cross-reactivity occurred between LPS from organisms in the different groups, this was insufficient to merit changes to the current LPS serogrouping system for T. hyodysenteriae. Besides this LPS ‘complex’, other higher-molecular-weight material which appeared to be a common component of the treponemes examined was present in low concentrations. Organisms with different serotypes within a serogroup apparently possessed common LPS bands, but also had unique LPS bands which may account for their serotype specificity. One ‘untypable’ organism lacked group-specific LPS and was thought to be a mutant of a group B organism. The loss of serogroup LPS by the isolate suggested that this material is an external component of the cell wall. The availability of an atypical organism lacking LPS components may facilitate further studies on the pathogenesis of swine dysentery.