The immunologically reactive part of immunopurified circulating anodic antigen from Schistosoma mansoni is a threonine-linked polysaccharide consisting of --> 6)-(beta-D-GlcpA-(1 --> 3))-beta-D-GalpNAc-(1 --> repeating units.
The gut-associated excretory antigen CAA (circulating anodic antigen) from adult Schistosoma mansoni worms was isolated by immunoaffinity chromatography. Amino acid analysis following alkaline borohydride treatment indicated that CAA is a glycoprotein, O-glycosylated at Thr. The primary structure of the released O-glycan moiety was investigated by one- and two-dimensional, homo- and heteronuclear 1H and 13C NMR spectroscopy. It was found that the major carbohydrate chains have a novel polysaccharide structure, consisting of a branched disaccharide repeating unit containing 2-acetamido-2-deoxy-beta-D- galactopyranose (beta-D-Galp-NAc) and beta-D-glucopyranuronic acid (beta-D-GlcpA). [formula: see text] The major antigenic character of CAA arises from this novel polysaccharide, which was shown to be an absolutely specific diagnostic marker in schistosomiasis. The cross-reactivity of CAA with anti-CCA (circulating cathodic antigen) monoclonal antibodies is caused by the presence of a small amount of O-linked CCA-poly-Lewis x carbohydrate chains on the CAA protein chain.
Bergwerff
A A
AA
Bijvoet Center Department of Bio-organic Chemistry, Utrecht University, The Netherlands.
van Dam
G J
GJ
Rotmans
J P
JP
Deelder
A M
AM
Kamerling
J P
JP
Vliegenthart
J F
JF
D000818:Animals; D000947:Antigens, Helminth / Q000737:chemistry*; D002240:Carbohydrate Sequence; D006023:Glycoproteins / Q000737:chemistry* / Q000276:immunology; D015801:Helminth Proteins / Q000737:chemistry* / Q000276:immunology; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000737:chemistry; D012550:Schistosoma mansoni / Q000276:immunology*
D000947:Antigens, Helminth; D006023:Glycoproteins; D015801:Helminth Proteins; D011134:Polysaccharides; C090907:circulating anodic antigen, Schistosoma mansoni