CRISPR/Cas9-mediated multiple single guide RNAs potently abrogate pseudorabies virus replication.

Pseudorabies virus (PRV) is a swine herpesvirus that causes significant morbidity and mortality in swine populations and has caused huge economic losses in the worldwide swine industry. Currently, there is no effective antiviral drug in clinical use for PRV infection; it is also difficult to eliminate PRV from infected swine. In our study, we set out to combat these swine herpesvirus infections by exploiting the CRISPR/Cas9 system. We designed 75 single guide RNAs (sgRNA) by targeting both essential and non-essential genes across the genome of PRV. We applied a firefly luciferase-tagged reporter PRV virus for high-throughput sgRNA screening and found that most of the sgRNAs significantly inhibited PRV replication. More importantly, using a transfection assay, we demonstrated that simultaneous targeting of PRV with multiple sgRNAs completely abolished the production of infectious viruses in cells. These data suggest that CRISPR/Cas9 could be a novel therapeutic agent against PRV in the future.