Figure 4.

Neutralizing SARS-CoV-2 infection by COVID-19 convalescent serum. (a) Schematic of experiment design. COVID-19 convalescent sera were diluted and incubated with SARS-CoV-2 before added to the media. At 48 h or 72 h post infection (p.i), the cytopathic effect (CPE) of the infected cells was examined. The viral RNAs in the supernatants were quantified by real-time PCR (q-PCR). (b) Quantification of the viral RNA levels in the supernatants from representative wells. Relative RNA levels to the mock-treated wells were plotted (n = 2). (c) Total anti-S antibody in the control sera and convalescent sera was examined by a chemiluminescence microparticle immunoassays (CMIA) assay and the reads were plotted. The sera with fully neutralizing activity were indicated in red.