Use of an artificial antigen containing the 3,6-di-O-methyl-beta-D-glucopyranosyl epitope for the serodiagnosis of leprosy.
The coupling of synthetic 3,6-di-O-methyl-beta-D-glucopyranosyl-(1----4)-2,3-di-O-methyl-alpha-L -rhamnopyranose, the hapten determinant of phenolic glycolipid I from Mycobacterium leprae, to bovine serum albumin (BSA) by reductive amination produced the antigen epsilon-N-1-[1-deoxy-2,3-di-O-methyl-4-O-(3',6'-di-O-methyl-beta -D-glucopyranosyl)-rhamnitol]-lysyl-BSA, which proved highly sensitive in ELISA and showed good concordance with the native glycolipid in analysis of serum samples from 223 leprosy patients. Conjugates prepared from 6-O-methyl-beta-D-glucopyranosyl- or beta-D-glucopyranosyl-containing disaccharides were inactive and those containing noncyclic 3,6-di-O-methyl-glucitol showed little activity. Thus 3,6-di-O-methyl-beta-D-glucopyranose in its cyclic hemiacetal form is necessary for binding anti-glycolipid IgM from leprosy patients. Analysis of serum samples from healthy subjects showed a false-positive rate of 2.4% (four of 169) against the glycolipid and 3.6% (six of 169) against the glycoconjugate. Comparable figures for samples of sera of tuberculosis patients were 3.0% (two of 66) and 9.0% (six of 66), respectively. Alternative synthesizing strategies may diminish this cross-reactivity. The prospects of a fully synthetic specific antigen for the worldwide serodiagnosis of leprosy look promising.
D000942:Antigens, Bacterial / Q000276:immunology*; D055598:Chemical Phenomena; D002621:Chemistry; D003429:Cross Reactions; D004187:Disaccharides / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes; D006017:Glycolipids / Q000276:immunology; D006241:Haptens / Q000276:immunology*; D006801:Humans; D007070:Immunoglobulin A / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis*; D007918:Leprosy / Q000145:classification / Q000175:diagnosis* / Q000276:immunology; D009166:Mycobacterium leprae / Q000276:immunology*; D012710:Serum Albumin, Bovine; D014376:Tuberculosis / Q000276:immunology
D000942:Antigens, Bacterial; D004187:Disaccharides; D000939:Epitopes; D006017:Glycolipids; D006241:Haptens; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D012710:Serum Albumin, Bovine; C042766:3,6-di-O-methyl-beta-glucopyranosyl-(1-4)-2,3-di-O-methyl-alpha-rhamnopyranose