Analysis of lipopolysaccharide antigens ofTreponema hyodysenteriae

Abstract

SUMMARYLipopolysaccharide (LPS) extracts obtained from Treponema hyodysenteriae of serogroups A, B, D and E, and from T. innocens were examined by SDSpolyacrylamide 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.

Serological grouping ofTreponema hyodysenteriae

“…These cross-reactivities were confirmed by Western blotting, the only differences being that antiserum against WAl reacted strongly with all the major components of QL LPS, and antiserum against QL reacted more weakly against Al LPS components than it did against its own LPS components. As in a previous study [7], some higher molecular weight bands were found to be shared by organisms from different serogroups.…”

“…It seems likely that in the future isolates will be found which clearly span one or more serogroups as currently defined, and when that occurs either the serogrouping system will need to be redefined or the organisms assigned to more than one serogroup. Some LPs components from the isolates examined by SDS-PAGE and Western blotting in this study had slightly different molecular weights from those previously recorded by us [7]. For example an LPS band in Al previously recorded at 12 kDa was recorded here at 19 kDa, and bands in WAI at 42 and 30 kDa were located at 38 and 23 kDa respectively in the present study.…”

“…Thus when the serum was absorbed with AI cells it would no longer react with low molecular weight LPS bands in Q1, although higher molecular weight material was still stained (membrane d). Previously these missing lower molecular weight LPS bands of T. hyodysenteriae (in the range 10-42 kDa) have been equated with serogroup antigens [7]. In contrast when this same antiserum was absorbed with WAI cells, the lower molecular weight bands in Q1 were still stained (as were those in Al, but much more weakly) whilst the higher molecular weight material was no longer visible (membrane f).…”

“…SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting of LPS from treponemes WAI, Al and Qi were conducted as previously described [7], using both unabsorbed antisera raised against these three isolates and sera which were cross-absorbed with each of the three isolates.…”

“…More recently it has been proposed that the organisms be arranged into five serogroups [6], with members of each group being defined by the reactivity of their LPS with rabbit serum raised against a 'type' organism for the serogroup. Serogroup antigens apparently consist of three or four major antigenic components in the 10-42 kDa range [7]. Within a serogroup, isolates which possess additional unique LPS antigens which can be identified using cross-absorbed sera can be regarded as serotypes or serovars within the serogroup [6].…”