ABSTRACT
Numerous host factors of SARS-CoV-2 have been identified by screening approaches, but delineating their molecular roles during infection and whether they can be targeted for antiviral intervention remains a challenge. Here we use Perturb-seq, a single-cell CRISPR screening approach, to investigate how CRISPR interference of host factors changes the course of SARS-CoV-2 infection and the host response in human lung epithelial cells. Our data reveal two classes of host factors with pronounced phenotypes: factors required for the response to interferon and factors required for entry or early infection. Among the latter, we have characterized the NF-{kappa}B inhibitor I{kappa}B (NFKBIA), as well as the translation factors EIF4E2 and EIF4H as strong host dependency factors acting early in infection. Overall, our study provides high-throughput functional validation of host factors of SARS-CoV-2 and describes their roles during viral infection in both infected and bystander cells.