COMPARATIVE-ANALYSIS OF BRUCELLA SEROTYPE A AND M AND YERSINIA-ENTEROCOLITICA O-9 POLYSACCHARIDES FOR SEROLOGICAL DIAGNOSIS OF BRUCELLOSIS IN CATTLE, SHEEP, AND GOATS

Hapten polysaccharides of Brucella smooth M and A serotypes were prepa red from Brucella sp. and Yersinia enterocolitica 0:9 by previously de scribed hydrolytic (O chain) or nonhydrolytic (native hapten [NH]) pro cedures. The purified polysaccharides differed only in the presence (O chain) or absence (NH) of lipopolysaccharide core sugars. The polysac charides were compared by reverse radial immunodiffusion for the diagn osis of brucellosis in cattle (Brucella abortus biotype 1 [A serotype] and Brucella melitensis biotype 3 [AM serotype]), sheep (B. melitensi s biotypes 1 [M serotype] and 3), and goats (B. melitensis biotype 1). The reverse radial immunodiffusion test with the NH from B. melitensi s 16 M (serotype M) showed the highest sensitivity (89.6 to 97.3%), re gardless of the host species and the serotype of the infecting Brucell a sp. Y. enterocolitica 0:9 NH (A serotype) was useful for diagnosing disease in cattle infected with B. abortus biotype 1, but not in cattl e infected with B. melitensis biotype 3, sheep, or goats. The differen t results obtained with the serotype M and A polysaccharides and the s era from animals infected with M, A, and AM serotypes of Brucella spp. showed that in naturally infected animals, a large proportion of the antibodies are directed to or react with a previously defined common e pitope(s) (J. T. Douglas and D. A. Palmer, J. Clin. Microbiol. 26:1353 -1356, 1988) different from the A or M epitopes. By using the radial i mmunodiffusion test with B. melitensis 16M NH, it was possible to diff erentiate infected from vaccinated cattle, sheep, and goats with a sen sitivity and specificity similar to that of the complement fixation te st.