KPNB1 and infection: Our screen also revealed that knock-out of sigma non-opioid intracellular receptor 1 (SIGMAR1) and NPC intracellular cholesterol transporter 1 (NPC1) enhanced cell survival and HCoV-229E infection, whereas knock-out of karyopherin subunit beta 1 (KPNB1) strongly downregulated both infection and cell viability (Fig. 3B).