PRNP and scrapie: Transgenic Drosophila that express membrane-bound VRQ ovine PrP (VRQ Drosophila fly line) and control non-transgenic flies (51D fly line) were exposed at the larval stage to brain material prepared from either PG127 scrapie-infected or healthy prion-free sheep (Thackray et al., 2012c, 2014).