The first description of a (1--> 6)-beta-D-glucan in prokaryotes: (1 --> 6)-beta-D-glucan is a common component of actinobacillus suis and is the basis for a serotyping system.
The chemical and antigenic properties of the cell-surface lipopolysaccharides (LPSs) and capsular polysaccharides (CPSs) of seven representative strains of Actinobacillus suis from healthy and diseased pigs were investigated. Four strains produced a linear (1 --> 6)-beta-D-glucan homopolymer, beta-D-Glcp-(1-[ --> 6)-beta-D-Glcp-(1-]n -->, as a LPS-O-chain (O1) and as a CPS (K1). Polyclonal antisera prepared against a (1 --> 6)-beta-D-glucan-containing strain showed a positive reaction against both LPSs and CPSs derived from the above strains (designated serotype O1/K1). One strain carried the (1 --> 6)-beta-D-glucan solely as a LPS-O-chain (serotype O1) and two strains did not express the (1 --> 6)-beta-D-glucan, but, instead, produced a different O-chain (designated serotype 02); these three strains expressed their own characteristic CPSs. (1 --> 6)-beta-D-Glucan structures are common cell wall components of yeast, fungi and lichens, but, to our knowledge, this is the first time a (1 --> 6)-beta-D-glucan has been described in a prokaryotic organism. Conformational and nuclear magnetic resonance analyses showed that the beta-D-Glcp-(1 --> 6)-beta-D-Glcp linkage was flexible and two distinct glycosidic conformers are described. Cross-reactive antibodies to the A. suis (1 --> 6)-beta-D-glucan could be detected in sera from a variety of species and in sera from specific pathogen free pigs. This cross-reactivity may arise from immuno-stimulation of organisms present in the surrounding environment that contain (1 --> 6)-beta-D-glucan, which may also explain the high incidence of false positive results in previous serological tests for A. suis. In addition, these (1 --> 6)-beta-D-glucan background antibodies may be protective against A. suis infection. The characterization herein of (1 --> 6)-beta-D-glucan is the foundation for the development of a serotyping system for A. suis.
Monteiro
M A
MA
Institute for Biological Sciences, National Research Council, Ottawa, Ont., Canada. mario.monteiro@nrc.ca
Slavic
D
D
St Michael
F
F
Brisson
J R
JR
MacInnes
J I
JI
Perry
M B
MB
D000188:Actinobacillus / Q000737:chemistry*; D000465:Algorithms; D000818:Animals; D000906:Antibodies / Q000378:metabolism; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D003429:Cross Reactions; D008401:Gas Chromatography-Mass Spectrometry; D005936:Glucans / Q000276:immunology* / Q000378:metabolism*; D007106:Immune Sera / Q000276:immunology; D015151:Immunoblotting; D008070:Lipopolysaccharides / Q000737:chemistry / Q000276:immunology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000276:immunology; D012703:Serotyping; D013552:Swine / Q000382:microbiology; D013816:Thermodynamics; D047071:beta-Glucans
D000906:Antibodies; D005936:Glucans; D007106:Immune Sera; D008070:Lipopolysaccharides; D011135:Polysaccharides, Bacterial; D047071:beta-Glucans; C064197:beta-1,6-glucan