The immunodominant 17-kDa antigen from Cryptosporidium parvum is glycosylphosphatidylinositol-anchored.
Cryptosporidium parvum is a protozoan parasite of the intestinal epithelium that has caused numerous outbreaks of diarrheal illness in humans. During our studies of the host immune response to C. parvum infection, we noted that two of the immunodominant surface antigens of the sporozoite stage of the parasite readily extract into Triton X-114. We recently cloned the immunodominant 17-kDa surface antigen and suggested that the carboxy-terminal peptide sequence may satisfy the requirements for GPI anchor addition. In the work presented here, we were able to show that the 17-kDa antigen could be metabolically labeled in vitro with tritiated ethanolamine and that the antigen contained myo-inositol. The antigen was cleaved by GPI-PLD but not by PI-PLC and it could be converted to a water soluble form by chemical deglycosylation. We suggest that the 17-kDa antigen is indeed GPI anchored and that the anchor contains an acylated inositol and either a lyso-acyl- or a diacyl-glycerol. We are currently working to determine what role the anchor may play in the human immune response to this antigen.
Division of Parasitic Diseases, Centers for Disease Control and Prevention, Public Health Service, U.S. Department of Health and Human Services, Mail Stop F-13, Building 23, Room 1025, 4770 Buford Highway N.E., Atlanta, GA 30341-3724, USA. jpriest@cdc.gov
J W
JW
Priest
L T
LT
Xie
M J
MJ
Arrowood
P J
PJ
Lammie
D000818:Animals; D000953:Antigens, Protozoan / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002849:Chromatography, Gas; D016785:Cryptosporidium parvum / Q000276:immunology*; D003902:Detergents; D004075:Diglycerides / Q000032:analysis; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D007294:Inositol / Q000032:analysis; D013058:Mass Spectrometry; D017830:Octoxynol; D010739:Phospholipase D / Q000494:pharmacology; D011092:Polyethylene Glycols; D017386:Sequence Homology, Amino Acid
D000953:Antigens, Protozoan; D003902:Detergents; D004075:Diglycerides; D017261:Glycosylphosphatidylinositols; D011092:Polyethylene Glycols; D007294:Inositol; D017830:Octoxynol; C010615:Nonidet P-40; D010739:Phospholipase D; C065017:glycoprotein phospholipase D