title: Bioassay of prion-infected blood plasma in PrP transgenic Drosophila.
abstract: In pursuit of a tractable bioassay to assess blood prion infectivity, we have generated prion protein (PrP) transgenic Drosophila, which show a neurotoxic phenotype in adulthood after exposure to exogenous prions at the larval stage. Here, we determined the sensitivity of ovine PrP transgenic Drosophila to ovine prion infectivity by exposure of these flies to a dilution series of scrapie-infected sheep brain homogenate. Ovine PrP transgenic Drosophila showed a significant neurotoxic response to dilutions of 10-2to 10-10of the original scrapie-infected sheep brain homogenate. Significantly, we determined that this prion-induced neurotoxic response in ovine PrP transgenic Drosophila was transmissible to ovine PrP transgenic mice, which is indicative of authentic mammalian prion detection by these flies. As a consequence, we considered that PrP transgenic Drosophila were sufficiently sensitive to exogenous mammalian prions to be capable of detecting prion infectivity in the blood of scrapie-infected sheep. To test this hypothesis, we exposed ovine PrP transgenic Drosophila to scrapie-infected plasma, a blood fraction notoriously difficult to assess by conventional prion bioassays. Notably, pre-clinical plasma from scrapie-infected sheep induced neurotoxicity in PrP transgenic Drosophila and this effect was more pronounced after exposure to samples collected at the clinical phase of disease. The neurotoxic phenotype in ovine PrP transgenic Drosophila induced by plasma from scrapie-infected sheep was transmissible since head homogenate from these flies caused neurotoxicity in recipient flies during fly-to-fly transmission. Our data show that PrP transgenic Drosophila can be used successfully to bioassay prion infectivity in blood from a prion-diseased mammalian host.
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 OES, U.K.
authors.forename: Alana M
authors.initials: AM
authors.lastname: Thackray
authors.affiliation: UMR INRA ENVT 1225 Hôtes-Agents Pathogènes, Ecole Nationale Vétérinaire de Toulouse, 23 Chemin des Capelles, 31076 Toulouse, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Andreoletti
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 OES, U.K.
authors.forename: Raymond
authors.initials: R
authors.lastname: Bujdoso
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001681:Biological Assay / Q000379:methods*; D001921:Brain / Q000378:metabolism; D004330:Drosophila; D029721:Drosophila Proteins / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D000072002:Prion Proteins / Q000235:genetics / Q000378:metabolism*; D011328:Prions / Q000472:pathogenicity*; D012608:Scrapie / Q000097:blood* / Q000378:metabolism*; D012756:Sheep
chemical_list: D029721:Drosophila Proteins; D000072002:Prion Proteins; D011328:Prions
keywords: Drosophila melanogaster; PrP; bioassay; prion; transmissible