Screening of candidate host cell membrane proteins involved in SARS-CoV-2 entry

Coronavirus disease (COVID-19) represents a real threat to the global population, and understanding the biological features of the causative virus, i.e., severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is imperative for mitigating this threat. Analyses of proteins such as primary receptors and co-receptors (co-factors), which are involved in the entry of SARS-CoV-2 into host cells, will provide important clues to help control the virus. Here, we identified host cell membrane protein candidates present in proximity to the attachment sites of SARS-CoV-2 spike proteins, using proximity labeling and proteomic analysis. The identified proteins represent key candidate factors that may be required for viral entry. DPP4, Cadherin-17, and CD133 were found to co-localize with cell membrane-bound SARS-CoV-2 spike proteins in Caco-2 cells and thus showed potential as candidate factors. The experimental infection with a SARS-CoV-2 pseudovirus indicated a 2-fold enhanced infectivity in the CD133-ACE2-coexpressing HEK293T cells compared to that in HEK293T cells expressing ACE-2 alone. The information and resources regarding these co-receptor labeling and analysis techniques could be utilized for the development of antiviral agents against SARS-CoV-2 and other emerging viruses.