Rescue of recombinant rSARS-CoV-2 and rSARS-CoV-2-GFP. The experimental setting is illustrated in the upper panel. Two clones of each construct 1-6 were used to prepare YAC DNAs and in-vitro transcribed viral genome RNAs were electroporated into BHK-21 cells and/or BHK-SARS-N together with an mRNA encoding the SARS-CoV-2 N protein. Electroporated cells were co-cultivated with VeroE6 cells in a T25 flask and cell culture supernatants were transferred to 12-well plates to perform plaque assay for rSARS-CoV-2 constructs 1-3 and fluorescence microscopy for rSARS-CoV-2-GFP constructs 4-6. Plaque assays are shown in the lower panel for SARS-CoV-2 clones 1.1, 2.2, and 3.1. VeroE6 cells were infected with 10−1, 10−2, and 10−3 dilutions of 1 ml supernatant from the individual rescue experiments and are compared to non-infected cells (Mock). The expression of GFP in SARS-CoV-2-GFP infected VeroE6 cells is shown for clones 4.1, 5.2, and 6.1. Mock represents non-infected VeroE6 cells. 