Immunocompromised Cas9 Transgenic Mice for Rapid Assessment of Host Factors Involved in Highly Pathogenic Virus Infection

Targeting host factors for anti-viral development offers several potential advantages over traditional countermeasures that include broad-spectrum activity and prevention of resistance. Characterization of host factors in animal models provides strong evidence of their involvement in disease pathogenesis, but the feasibility of performing high-throughput analyses on lists of genes is problematic. To begin addressing the challenges of screening candidate host factors , we combined advances in CRISPR-Cas9 genome editing with an immunocompromised mouse model used to study highly pathogenic viruses. Transgenic mice harboring a constitutively expressed allele ( ) with or without knockout of type I interferon receptors served to optimize delivery of CRISPR single-guide RNA (sgRNA) using Invivofectamine 3.0, a simple and easy-to-use lipid nanoparticle reagent. Invivofectamine 3.0-mediated liver-specific editing to remove activity of the critical Ebola virus host factor Niemann-Pick disease type C1 in an average of 74% of liver cells protected immunocompromised mice from lethal surrogate Ebola virus infection. We envision that immunocompromised mice combined with straightforward sgRNA delivery will enable efficient host factor loss-of-function screening in the liver and other organs to rapidly study their effects on viral pathogenesis and help initiate development of broad-spectrum, host-directed therapies against emerging pathogens.