Classical scrapie diagnosis in ARR/ARR sheep in Brazil
Leal, Juliano SouzaAndrade, Caroline Pinto deCorrea, Gabriel Laizola FrainerBoos, Gisele SilvaBianchi, Matheus ViezzerSilva, Sergio Ceroni daLopes, Rui Fernando FelixDriemeier, David
Background: Scrapie is a transmissible spongiform encephalopathy (TSE) that affects sheep flocks and goat herds. The transfer of animals or groups of these between sheep farms is associated with increased numbers of infected animals and with the susceptibility or the resistance to natural or classical scrapie form. Although several aspects linked to the etiology of the natural form of this infection remain unclarified, the role of an important genetic control in scrapie incidence has been proposed. Polymorphisms of the PrP gene (prion protein, or simply prion), mainly in codons 136, 154, and 171, have been associated with the risk of scrapie.Case: One animal from a group of 292 sheep was diagnosed positive for scrapie in the municipality of Valparaíso, state of São Paulo, Brazil. The group was part of a flock of 811 free-range, mixed-breed Suffolk sheep of the two genders and ages between 2 and 7 years from different Brazilian regions. Blood was collected for genotyping (for codons 136, 141, 154 and 171), and the third lid and rectal mucosa were sampled for immunohistochemistry (IHC) for scrapie, from all 292 animals of the group. IHC revealed that seven (2.4%) animals were positive for the disease. Collection of samples was repeated for 90 animals, among which the seven individuals diagnosed positive and 83 other animals that had some degree of kinship with those. These 90 she...(AU)
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