Synthetic oligosaccharides as tools to demonstrate cross-reactivity between polysaccharide antigens.
Escherichia coli O148 is a nonencapsulated enterotoxigenic (ETEC) Gram negative bacterium that can cause diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome in humans. The surface-exposed O-specific polysaccharide (O-SP) of the lipopolysaccharide of this bacterium is considered both a virulence factor and a protective antigen. It is built up of the linear tetrasaccharide repeating unit [3)-α-L-Rhap-(1→2)-α-D-Glcp-(1→3)-α-D-GlcNAcp-(1→3)-α-L-Rhap-(1→] differing from that of the O-SP of Shigella dysenteriae type 1 (SD) only in that the latter contains a D-Galp residue in place of the glucose moiety of the former. The close similarity of the O-SPs of these bacteria indicated a possible cross-reactivity. To answer this question we synthesized several oligosaccharide fragments of E. coli O148 O-SP, up to a dodecasaccharide, as well as their bovine serum albumin or recombinant diphtheria toxin conjugates. Immunization of mice with these conjugates induced anti-O-SP-specific serum IgG antibody responses. The antisera reacted equally well with the LPSs of both bacteria, indicating cross-reactivity between the SD and E. coli O148 O-SPs that was further supported by Western-blot and dot-blot analyses, as well as by inhibition of binding between the antisera and the O-SPs of both bacteria.
Program on Developmental and Molecular Immunity, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-2423, USA. pozsgayv@mail.nih.gov
Vince
V
Pozsgay
Joanna
J
Kubler-Kielb
Bruce
B
Coxon
Paul
P
Santacroce
John B
JB
Robbins
Rachel
R
Schneerson
D002236:Carbohydrate Conformation; D003429:Cross Reactions / Q000276:immunology*; D004926:Escherichia coli / Q000737:chemistry / Q000276:immunology*; D008969:Molecular Sequence Data; D019081:O Antigens / Q000737:chemistry / Q000276:immunology*; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry / Q000276:immunology*
D019081:O Antigens; D009844:Oligosaccharides