ART4 and COVID-19: In order to determine virus-neutralizing antibody levels in sera collected from convalescent COVID-19 patients, we employed a biosafety level 1 compliant pseudotype virus neutralization (PVN) test using VSV*ΔG(FLuc), a propagation-incompetent vesicular stomatitis virus (VSV) that lacked the glycoprotein (G) gene but harbored the reporter genes green fluorescent protein (GFP) and firefly luciferase (FLuc) instead [14].