Epitope scanning reveals gain and loss of strain specific antibody binding epitopes associated with the conversion of normal cellular prion to scrapie prion.
We used anti-prion (PrP) monoclonal antibodies (Mabs) in different combinations to scan changes in the availability of antibody binding epitopes--using an epitope scanning assay--in brain homogenates from normal mice, and from mice infected with either ME7 or 139 A strains of infectious scrapie prion (PrPSc). In ME7-infected brains, the epitope detected by the Mab pair 8B4/8H4 is reduced, while the epitope detected by the Mab pair 8F9/11G5 is increased. Mab 8F9/11G5 detect a conformational epitope on PrPSc because the rise in Mab 8F9/11G5 binding is sensitive to a denaturing agent but resistant to proteinase K (PK). While the increase in Mab 8F9/11G5 binding correlates with the presence of PK-resistant PrP and clinical signs of infection, the reduction in Mab 8B4/8H4 binding is detected earlier. Fractionation of the ME7-infected brain homogenate in sucrose gradient revealed that the PrPSc species detected by the epitope scanning assay are heterogeneous in size, with a molecular mass of approximately > or = 2000-kDa. We also investigated whether these findings were applicable to two other strains of PrPSc, namely 87 V and 22 L. We found that the decrease in Mab 8B4/8H4 binding detected in ME7-infected brains was also detected in 87 V-infected brains but not in 22 L-infected brains. In contrast, the increase in Mab 8F9/11G5 binding detected in ME7- and 139 A-infected brains was also detected in 22 L-infected brains but not in 87 V-infected brains. Therefore, each prion strain has its unique conformation, and we can monitor the conversion of normal cellular prion (PrPC) to PrPSc based on the changes in the antibody binding patterns. The epitope can be decreased or increased, linear or conformational, detected late or early during infection, in a strain specific manner.
Pan
Tao
T
Institute of Pathology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 10900, USA.
Li
Ruliang
R
Kang
Shin-Cheng
SC
Wong
Boon-Seng
BS
Wisniewski
Thomas
T
Sy
Man-Sun
MS
D000409:Alanine / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D000911:Antibodies, Monoclonal / Q000378:metabolism; D001666:Binding Sites, Antibody / Q000276:immunology*; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004306:Dose-Response Relationship, Immunologic; D019286:Endopeptidase K / Q000494:pharmacology; D018604:Epitope Mapping / Q000379:methods; D000939:Epitopes / Q000276:immunology*; D005260:Female; D007158:Immunologic Techniques; D007930:Leucine / Q000378:metabolism; D008297:Male; D008715:Methionine / Q000378:metabolism; D051379:Mice; D018622:PrP 27-30 Protein / Q000276:immunology; D018620:PrPSc Proteins / Q000737:chemistry / Q000378:metabolism*; D011233:Precipitin Tests / Q000379:methods; D011328:Prions / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism*; D011994:Recombinant Proteins; D012608:Scrapie / Q000276:immunology*; D013045:Species Specificity; D014633:Valine / Q000378:metabolism
D000911:Antibodies, Monoclonal; D000939:Epitopes; D018620:PrPSc Proteins; D011328:Prions; D011994:Recombinant Proteins; D018622:PrP 27-30 Protein; D008715:Methionine; D019286:Endopeptidase K; D007930:Leucine; D014633:Valine; D000409:Alanine