Production and titration of SARS-CoV-2 pseudovirus
A pseudovirus strain of SARS-Cov-2 Omicron BA.1 and BA.5 variants were
constructed with more than 32 mutations in the S protein. Pseudoviruses
of the prototype was also constructed. The SARS-CoV-2 pseudovirus was
prepared by transfecting 293T cells with S protein expression plasmids.
And G*ΔG-VSV (Kerafast, Boston, MA) was added by providing genomes of
VSV. Following collection and filtering, the pseudotyped viruses were
titered on Vero cells (8). Briefly described, the pseudotyped viruses
were diluted from 1:10 to 1:7290 by three-fold serial dilutions, and
mixed with Vero cells (2x104 / well) in 96-well
plates. The mixture was incubated at 37°C, 5% CO2 for
24 h. The chemiluminescence signals were collected using the Britelite
plus reporter gene assay system (PerkinElmer, Waltham, MA). The 50%
tissue culture infective dose (TCID50) was calculated using the
Reed-Muench method.