Fig. 1.

Combination of a pseudovirus assay and protein-based assays enabled identification of novel inhibitors targeting the early stage of coronavirus infection. a) Schematic representation of a compound screen using a pseudovirus presenting the spike of MERS-CoV. To generate the pseudovirus, a lentivirus backbone, luciferase gene, and the spike were transfected onto 293T cells. In the compound screen, Huh-7 cells were treated with compounds and infected with the pseudovirus, after which the accumulated luciferase signal was measured. b) Schematic representation of the alpha test. In the alpha test, the receptor binding domain (RBD) of the spike of MERS-CoV was immobilized on the donor bead while its cellular receptor, hDPP4 was attached to an acceptor bead. c) Summary of classification of hits from the pseudovirus screen and subsequent alpha test: ∼16% entry-specific (spike-specific) compounds among 1126 hits. d) Structure of three identified hits: thiosemicarbazide, amiodarone, and raloxifene.