Mass spectrometric analysis of the immunodominant glycan epitope of Echinococcus granulosus antigen Ag5

• Published in: International journal for parasitology Vol. 42; no. 3; pp. 279 - 285
• Main Authors: Paschinger, Katharina, Gonzalez-Sapienza, Gualberto G., Wilson, Iain B.H.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.03.2012; Elsevier; Elsevier Science
• Subjects: Amino Acid Sequence; Animals; Antibodies, Helminth - immunology; Antigenicity; Antigens, Helminth - chemistry; Antigens, Helminth - genetics; Antigens, Helminth - immunology; Biological and medical sciences; C-reactive protein; Cestoda; Echinococcosis - immunology; Echinococcosis - parasitology; Echinococcus; Echinococcus granulosus; Echinococcus granulosus - chemistry; Echinococcus granulosus - genetics; Echinococcus granulosus - immunology; Epitopes; Fundamental and applied biological sciences. Psychology; Glycan; Glycopeptides; Humans; Immunodominant Epitopes - chemistry; Immunodominant Epitopes - genetics; Immunodominant Epitopes - immunology; Immunoreactivity; Life cycle. Host-agent relationship. Pathogenesis; Mass Spectrometry; Mass spectroscopy; Molecular Sequence Data; Monoclonal antibodies; N-glycans; Phosphorylcholine; Polysaccharides; Polysaccharides - chemistry; Polysaccharides - immunology; Protozoa; Sugar; Western blotting; Glycan; Echinococcus; Phosphorylcholine; Antigen; Mass; Helmintha; Plathelmintha; Parasite; Cestoda; Invertebrata; Echinococcus granulosus
• ISSN: 0020-7519; 1879-0135
• DOI: 10.1016/j.ijpara.2012.01.002

[Display omitted] ► Echinococcus granulosus antigen, Ag5, possesses an immunodominant glycan epitope. ► The N-glycans and glycopeptides of the E. granulosus Ag5 38kDa subunit were analysed by mass spectrometry. ► Analyses verified the presence of phosphorylcholine on a cestode protein. In previous work we showed that Ag5, a major diagnostic antigen from the metacestode of Echinococcus granulosus, possesses a dominant sugar epitope that upon removal results in abolition of most of the antigen immunoreactivity with patient sera. Analysis of this glycan modification has now been performed by western blotting and mass spectrometry. Reactivity to both a specific monoclonal antibody (TEPC15) and human C-reactive protein as well as the presence of a modification of 165 mass units, as detected by mass spectrometry of both glycopeptides and released N-glycans, indicated that the immunodominant sugar epitope of the Ag5 38kDa subunit is a biantennary structure modified by phosphorylcholine. We believe this is the first time that such a modification has been proven in cestodes and provides the structural basis for understanding the antigenicity of this major E. granulosus component.