Fig. 2

Neutralizing activity of COVID-19 patient sera against and SARS-CoV-2 pseudotyped MLV. a Serum samples from COVID-19 patients were pre-incubated with SARS-CoV-2 spike pseudotyped MLV at 37 °C for 1 h. Sera and virus mixture were then incubated with HEK293T-ACE2 cells for 2 days. SARS-CoV-2 spike RBD was used as a positive control. SIV gp130 was used as a negative control. Luciferase was measured to assess infection. b Neutralization titer 50, 80 and 90 (NT₅₀, NT_80, NT₉₀) were calculated as the reciprocal of the dilution resulting in 50, 80 and 90% neutralization, respectively. ELISA tests by Abbott and Euroimmun are not quantitative. Positive samples for the Abbott test are ≥ 1.4 and for the Euroimmun test ≥ 1.1