Immunohistochemical detection of scrapie prion proteins in clinically normal sheep in Pennsylvania.
Following diagnosis of scrapie in a clinically suspect Suffolk sheep, 7 clinically normal flockmates were purchased by the Pennsylvania Department of Agriculture to determine their scrapie status using an immunohistochemical procedure. Two of the 7 euthanized healthy sheep had positive immunohistochemical staining of the prion protein of scrapie (PrP-Sc) in their brains, nictitating membranes, and tonsils. The PrP-Sc was localized in the areas of the brain where, histopathologically, there was neurodegeneration and astrocytosis. The PrP-Sc occurred within germinal centers of the affected nictitating membranes and tonsils and was located in the cytoplasm of the dendrite-like cells, lymphoid cells, and macrophages. These results confirm that immunohistochemical examination of the nictitating membrane can be used as a screen for the presence of scrapie infection in clinically normal sheep at a capable veterinary diagnostic laboratory. In sheep with a PrP-Sc-positive nictitating membrane, the diagnosis of scrapie should be confirmed by histopathology and immunohistochemical examination of the brain following necropsy. Following full validation, immunohistochemistry assays for detection of PrP-Sc in nictitating membrane lymphoid tissues can improve the effectiveness of the scrapie control and eradication program by allowing diagnosis of the disease in sheep before the appearance of clinical signs.
Pennsylvania Animal Diagnostic Laboratory System, Pennsylvania Veterinary Laboratory, Harrisburg 17025, USA.
H
H
Kim
K I
KI
O'Rourke
M
M
Walter
H G
HG
Purchase
J
J
Enck
T K
TK
Shin
D000818:Animals; D001921:Brain / Q000473:pathology; D007150:Immunohistochemistry; D009541:Nictitating Membrane; D010414:Pennsylvania; D018620:PrPSc Proteins / Q000032:analysis* / Q000276:immunology; D012608:Scrapie / Q000175:diagnosis* / Q000276:immunology; D012680:Sensitivity and Specificity; D012756:Sheep
D018620:PrPSc Proteins