Exocyst complex component 2 is a potential host factor for SARS-CoV-2 infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused an epidemic and spread rapidly all over the world. Because the analysis of host factors other than receptors and proteases has not been sufficiently performed, we attempted to identify and characterize host factors essential for SARS-CoV-2 infection using iPS cells and airway organoids (AO). Based on previous CRISPR screening and RNA-seq data, we found that exocyst complex component 2 (EXOC2) is one important host factor for SARS-CoV-2 infection. The intracellular SARS-CoV-2 nucleocapsid (N) expression level was decreased to 3.7% and the virus copy number in cell culture medium was decreased to 1.6% by EXOC2 knockdown. Consistently, immunostaining results showed that N protein-positive cells were significantly decreased by EXOC2 knockdown. We also found that EXOC2 knockdown downregulates SARS-CoV-2 infection by regulating IFNW1 expression. In conclusion, controlling the EXOC2 expression level may prevent SARS-CoV-2 infection and deserves further study.

Dual inhibition of TMPRSS2 and Cathepsin Bprevents SARS-CoV-2 infection in iPS cells.

It has been reported that many receptors and proteases are required for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Although angiotensin-converting enzyme 2 (ACE2) is the most important of these receptors, little is known about the contribution of other genes. In this study, we examined the roles of neuropilin-1, basigin, transmembrane serine proteases (TMPRSSs), and cathepsins (CTSs) in SARS-CoV-2 infection using the CRISPR interference system and ACE2-expressing human induced pluripotent stem (iPS) cells. Double knockdown of TMPRSS2 and cathepsin B (CTSB) reduced the viral load to 0.036% ± 0.021%. Consistently, the combination of the CTPB inhibitor CA-074 methyl ester and the TMPRSS2 inhibitor camostat reduced the viral load to 0.0078% ± 0.0057%. This result was confirmed using four SARS-CoV-2 variants (B.1.3, B.1.1.7, B.1.351, and B.1.1.248). The simultaneous use of these two drugs reduced viral load to less than 0.01% in both female and male iPS cells. These findings suggest that compounds targeting TMPRSS2 and CTSB exhibit highly efficient antiviral effects independent of gender and SARS-CoV-2 variant.