An assessment of the efficiency of PrPsc detection in rectal mucosa and third-eyelid biopsies from animals infected with scrapie.
In classical scrapie, detection of PrPsc on lymphoreticular system is used for the in vivo and post mortem diagnosis of the disease. However, the sensitivity of this methodology is not well characterised because the magnitude and duration of lymphoid tissue involvement can vary considerably. The aim of the present study was to evaluate the efficiency of detecting PrPsc in rectal mucosa and third-eyelid biopsies. A total of 474 genetically susceptible sheep and 24 goats from three scrapie infected flocks were included in this study. A sample from rectal mucosa and a sample from third-eyelid lymphoid tissue were collected from each animal. Biopsy samples were fixed in formaldehyde and processed for immunohistochemical examination. Animals with negative biopsy results were studied more closely through a post mortem examination of central nervous and lymphoreticular systems and if there was a positive result, additional biopsy sections were further tested. The sensitivity of rectal mucosa and third-eyelid assays were 36% and 40% respectively on initial examination but increased to 48% and 44% respectively after retesting. The results of this field study show a high percentage of infected animals that do not have detectable levels of PrPsc in the biopsied lymphoid tissue, due mainly to the relatively high number of animals with minimal or no involvement of lymphoid tissue in the pathogenesis of the disease.
Monleón
Eva
E
Centro de Investigación en Encefalopatías y Enfermedades Transmisibles Emergentes, Universidad de Zaragoza, C/ Miguel Servet 177, 50013 Zaragoza, Spain. emonleon@unizar.es
Garza
Ma Carmen
MC
Sarasa
Rocío
R
Alvarez-Rodriguez
Javier
J
Bolea
Rosa
R
Monzón
Marta
M
Vargas
M Antonia
MA
Badiola
Juan José
JJ
Acín
Cristina
C
D000818:Animals; D001706:Biopsy / Q000662:veterinary; D005838:Genotype; D006041:Goats / Q000235:genetics; D007413:Intestinal Mucosa / Q000473:pathology*; D008221:Lymphoid Tissue / Q000473:pathology; D009541:Nictitating Membrane / Q000473:pathology*; D018620:PrPSc Proteins / Q000378:metabolism*; D015203:Reproducibility of Results; D012608:Scrapie / Q000175:diagnosis* / Q000473:pathology*; D012680:Sensitivity and Specificity; D012756:Sheep / Q000235:genetics
D018620:PrPSc Proteins