Abstract
Prions are transmissible protein pathogens most reliably detected by a bioassay in a suitable host, typically mice. However, the mouse bioassay is slow and cumbersome, and relatively insensitive to low titers of prion infectivity. Prions can be detected biochemically in vitro by the protein misfolding cyclic amplification (PMCA) technique, which amplifies disease-associated prion protein but does not detect bona fide prion infectivity. Here, we demonstrate that Drosophila transgenic for bovine prion protein (PrP) expression can serve as a model system for the detection of bovine prions significantly more efficiently than either the mouse prion bioassay or PMCA. Strikingly, bovine PrP transgenic Drosophila could detect bovine prion infectivity in the region of a 10−12 dilution of classical bovine spongiform encephalopathy (BSE) inoculum, which is 106-fold more sensitive than that achieved by the bovine PrP mouse bioassay. A similar level of sensitivity was observed in the detection of H-type and L-type atypical BSE and sheep-passaged BSE by bovine PrP transgenic Drosophila. Bioassays of bovine prions in Drosophila were performed within 7 weeks, whereas the mouse prion bioassay required at least a year to assess the same inoculum. In addition, bovine PrP transgenic Drosophila could detect classical BSE at a level 105-fold lower than that achieved by PMCA. These data show that PrP transgenic Drosophila represent a new tractable prion bioassay for the efficient and sensitive detection of mammalian prions, including those of known zoonotic potential.
Highlights
Animal prion diseases are a significant public health risk through their potential for zoonotic transmission [6]
No prion-seeding activity was detected in the head homogenate prepared from 5- or 10-day-old bovine prion protein (PrP) Drosophila that had been exposed to classical bovine spongiform encephalopathy (BSE) at the larval stage
We showed that the sensitivity of bovine PrP Drosophila for classical BSE prions determined by detection of prion-seeding activity correlated with the level of prioninduced neurotoxic phenotype seen in these flies, which was assessed by negative geotaxis climbing assay or survival
Summary
A new model for sensitive detection of zoonotic prions by PrP transgenic Drosophila. Thackray , Olivier Andréoletti, John Spiropoulos, and Raymond Bujdoso1,* From the 1Department of Veterinary Medicine, University of Cambridge, Cambridge, UK; 2UMR INRA ENVT 1225 -Hôtes-Agents Pathogènes, Ecole Nationale Vétérinaire de Toulouse, Toulouse, France; 3Pathology Department, Animal and Plant Health Agency (APHA), Weybridge, Addlestone, Surrey, UK
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