Figure 4.

Detection of neutralizing antibodies against D614G, B.1.1.7 and B.1.617 pseudotyped viruses in ZF2001 vaccinee serum samples. (A–C) Neutralizing activity of ZF2001 (RBD-subunit vaccine) sera to D614G, B.1.1.7 and B.1.617. Two individuals who received three doses (A) and eight individuals who received two doses (B) of ZF2001. Pseudotypes were incubated with different serum dilutions for 60 min at 37 °C, and then were incubated onto 293T-ACE2 cells. Upon 72 h, cells were lysed with passive lysis buffer and the activity of firefly luciferase was analyzed. The half-maximal neutralizing titer (ID₅₀) was quantitatively analyzed using Graphpad 8.0 and the threshold of ID₅₀ was 1:40. (C) The GMT values and changes in ZF2001 vaccinee sera ID₅₀ against D614G, B.1.1.7 and B.1.617.