Identification and characterization of glycosylphosphatidylinositol-linked Schistosoma mansoni adult worm immunogens.
Metabolic radiolabeling of adult worms of Schistosoma mansoni with [3H]myristic acid has revealed that the fatty acid is incorporated into more than 15 proteins. We have shown that two of these proteins, a 200-kDa glycoprotein known to be exposed on the surface of the adult worm following praziquantel treatment and a 22-kDa glycoprotein that shows an enhanced immune reactivity with sera of vaccinated mice, are anchored to the adult worm membrane via a glycosylphosphatidylinositol (GPI) linkage. Both antigens partitioned preferentially into the detergent phase of Triton X-114 and were susceptible, following immunoaffinity purification, to hydrolysis by phosphatidylinositol-specific phospholipase C (PIPLC) from Bacillus thuringiensis and phospholipase C from Bacillus cereus. Diacylglycerol (DAG) was released following hydrolysis by bacterial PIPLC; however, Trypanosoma brucei GPIPLC failed to release the diacylglycerol from either protein. Treatment with nitrous acid generated phosphatidylinositol (PI) from both proteins, and phospholipase D from rat serum cleaved phosphatidic acid from the 200-kDa protein. Although the functional significance of these GPI-anchored proteins is unknown, their release from the surface of the schistosome may contribute to immune evasion.
Sauma
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SY
Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
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D000818:Animals; D000947:Antigens, Helminth / Q000032:analysis*; D005260:Female; D006017:Glycolipids / Q000032:analysis*; D017261:Glycosylphosphatidylinositols; D008715:Methionine / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008970:Molecular Weight; D009226:Myristates / Q000378:metabolism; D009608:Nitrous Acid; D010716:Phosphatidylinositols / Q000032:analysis*; D010739:Phospholipase D; D011223:Praziquantel / Q000494:pharmacology; D011233:Precipitin Tests; D012550:Schistosoma mansoni / Q000276:immunology*; D013462:Sulfur Radioisotopes; D014316:Tritium; D010738:Type C Phospholipases
D000947:Antigens, Helminth; D006017:Glycolipids; D017261:Glycosylphosphatidylinositols; D009226:Myristates; D010716:Phosphatidylinositols; D013462:Sulfur Radioisotopes; D014316:Tritium; D011223:Praziquantel; D008715:Methionine; D010738:Type C Phospholipases; D010739:Phospholipase D; D009608:Nitrous Acid