P selectin promotes SARS-CoV-2 interactions with platelets and the endothelium.

The physiology of SARS-CoV-2 virus/host interactions is not well understood. To better understand host/virus interactions, we performed a CRISPR activation screen to identify host genes that confer resistance to authentic SARS-CoV-2. This highlighted 34 new candidate genes that may alter the course of infection. We validated that 7 of these genes can suppress authentic SARS-CoV-2 infection, including the innate immune receptor P selectin, which increases SARS-CoV-2 spike-dependent binding to cells, while protecting from infection. P selectin also promotes binding to SARS-CoV-2 variants, SARS-CoV-1, and Middle East respiratory syndrome spike proteins, suggesting a general role for P selectin in highly pathogenic coronavirus infections. Importantly, P selectin protein expression driven by synthetic mRNA can block SARS-CoV-2 infection. Naturally, P selectin is expressed on platelets, and we show that it promotes spike-mediated platelet aggregation. P selectin is also expressed on the endothelium, where SARS-CoV-2 spike interactions are also P selectin dependent. In vivo, SARS-CoV-2 uses P selectin to home to capillary beds where the virus interacts with platelets and endothelium, and blocking this interaction can clear vascular-associated pulmonary SARS-CoV-2.