Lipopolysaceharide from serostrains of Serpulina (Treponema) hyodysenteriae for serogroups A to I was characterized using sodium dodecylsulphate polyacrylamide gel electrophoresis and silver staining. All strains had lipo-polysaccharide components ranging from 10 to 16 kDa that represented lipid A-core polysaccharide regions, and short O-antigen side chain were also recognized in certain immunoblots.
Serological reactions between lipopolysaceharide and antisera against each of these serostrains were examined by Western immunoblotting. There was relatively little antigenic cross-reactivity between LPS from the nine strains, thus confirming their suitability as serostrains.
Using cross-absorbed sera, isolates within serogroups A and E were shown to possess unique epitopes on the core lipopolysaceharide, distinct from serogroup reactivities. These isolates were therefore identified as serovars within the serogroups.
This study confirmed the usefulness of the serotyping scheme for S. hyodysenteriae, in which the bacteria can be placed into serogroups using unabsorbed sera, and into serovars within these using cross-absorbed sera.