CRISPR editing of candidate host factors that impact influenza A virus infection

Influenza A virus (IAV) is a respiratory pathogen with a segmented negative-sense RNA genome that is capable of causing epidemics and pandemics. The error-prone nature of the IAV polymerase results in antigenic drift and antigenic shift which contribute to low vaccine efficacy and escape from antivirals. The host factors required for the complete IAV infectious cycle have not been fully identified. Here, we examined select host factors that were identified by independent CRISPR screens as candidate contributors to IAV infectivity. We performed CRISPR-mediated knockout of cytidine monophosphate N-acetylneuraminic acid synthetase (CMAS) as well as CRISPR-mediated overexpression of beta-1,4 N-acetylgalactosaminyltransferase 2 (B4GALNT2) and adenosine deaminase acting on RNA 1 (ADAR1) in the human bronchial epithelial A549 cell line and evaluated for reduction of IAV infection. We confirmed that the knockout of CMAS or overexpression of B4GALNT2 restricts IAV infection by diminishing binding to the cell surface. While ADAR1 overexpression did not significantly inhibit IAV replication, it had a pro-viral effect with coxsackie B virus infection. Taken together, these data provide insight into how host factors identified in CRISR screens can modulate IAV infection and be utilized to further understand the IAV life cycle and for developing antiviral strategies.