Proposed revisions to the serological typing system forTreponema hyodysenteriae

Abstract

SUMMARYAntisera were prepared in rabbits against seven well-characterized strains of Treponema hyodysenteriae of known serotype, and reacted in agarose gel double immunodiffusion tests (AGDP) with lipopolysaccharide (LPS) extracted from 18 Western Australian isolates of the organism. Eight isolates were provisionally typed by this method, but sera raised against one 'typed' and two 'untypable' local isolates reacted in an unexpected fashion with LPS from other local and type strains. Serum raised against the 'typed' local isolate reached with LPS from other previously untyped local isolates: this indicated the presence of more than one major LPS antigen amongst certain local isolates, and was confirmed by crossabsorption of sera. Sera raised against apparently untypable local isolates reacted with LPS from certain type organisms, thus suggesting the presence of complex antigenic relationships between LPS antigens.The serotyping system for T. hyodysenteriae which was proposed by Baum & Joens (1979) uses unabsorbed antisera and is made unworkable by these observations. Instead we propose placing organisms which share common LPS antigens into serogroups A to E, members of which are defined by their reactivity with unabsorbed sera raised against a type organism for the group. We suggest strains B78, WAI, B169, Al and WA6 respectively as being the most suitable type organisms for the five serogroups identified so far. Isolates possessing additional unique LPS antigens can be regarded as serotypes within the serogroup. However the serotype of an isolate can only be established if antiserum is prepared against it, and this serum continues to react homologously after cross-absorption with bacteria from other serotypes within the serogroup.

Reclassification of Treponema hyodysenteriae and Treponema innocens in a New Genus, Serpula gen. nov., as Serpula hyodysenteriae comb. nov. and Serpula innocens comb. nov.

“…Classification of strains according to serotypes is based on soluble antigens found in the water phase of cells extracted with hot phenol-water (2,10,32).…”

Slide-agglutination for rapid serological typing of Treponema hyodysenteriae

“…Treponema hyodysenteriae strains B78, WAI, B169, Al, WA6, Vict. Q16.. Vic2 and NSW1 are type strains for serogroups A to I respectively [4][5][6]. The other 24 T. hyodysenteriae isolates used in the study were confirmed as such on the basis of their strong beta-haemolysis on 5 % defibrinated sheep blood agar, production of indole, and characteristic biochemical profile in the API-ZYM test [9].…”

“…hyodysenteriae isolates were serogrouped in AGDP as previously described, using rabbit antisera prepared against the 'type strains' of the nine serogroups [4][5][6].…”

“…These bacteria can be typed for epidemiological studies using serological methods [3,4]. This procedure involves extracting lipopolysaccharide (LPS) from the isolate to be typed, and reacting this in agarose gel double diffusion precipitation tests (AGDP) with hyperimmune rabbit antisera raised against type strains of the main serogroups of T. hyodysenteriae [4]. To date nine serological groups of the bacteria have been described [4][5][6].…”

“…This procedure involves extracting lipopolysaccharide (LPS) from the isolate to be typed, and reacting this in agarose gel double diffusion precipitation tests (AGDP) with hyperimmune rabbit antisera raised against type strains of the main serogroups of T. hyodysenteriae [4]. To date nine serological groups of the bacteria have been described [4][5][6]. Immunity against T. hyodysenteriae infection in colonic loops is LPS-serotype specific [7], and bacterin vaccines confer the best protection when subsequent infection is with an homologous LPS-serotype of the bacteria [8].…”