Gene-edited murine cell lines for propagation of chronic wasting disease prions

Prions cause fatal infectious neurodegenerative diseases in humans and animals. Cell culture models are essential for studying the molecular biology of prion propagation. Defining such culture models is mostly a random process, includes extensive subcloning, and for many prion diseases few or no models exist. One example is chronic wasting disease (CWD), a highly contagious prion disease of cervids. To extend the range of cell models propagating CWD prions, we gene-edited mouse cell lines known to efficiently propagate murine prions. Endogenous prion protein (PrP) was ablated in CAD5 and MEF cells, using CRISPR-Cas9 editing. PrP knock-out cells were reconstituted with mouse, bank vole and cervid PrP genes by lentiviral transduction. Reconstituted cells expressing mouse PrP provided proof-of-concept for re-established prion infection. Bank voles are considered universal receptors for prions from a variety of species. Bank vole PrP reconstituted cells propagated mouse prions and cervid prions, even without subcloning for highly susceptible cells. Cells reconstituted with cervid PrP and infected with CWD prions tested positive in prion conversion assay, whereas non-reconstituted cells were negative. This novel cell culture platform which is easily adjustable and allows testing of polymorphic alleles will provide important new insights into the biology of CWD prions.