Figure 4. Neutralization of virus pseudotyped with SARS-CoV-2 Wuhan Hu-1 spikes by human mAbs.
Highly mutated mAbs were cloned and expressed on 293T/17 cells. The supernatants were collected, and the amount of IgG was measured by ELISA. Serially diluted Abs were incubated with viruses pseudotyped with the reference (Wuhan Hu-1) or mutant spikes, and infection of 293T-ACE2 cells was assessed by luminescence. The Ab concentration that inhibits 50% of infection (IC50) was calculated for each sample. (A) The neutralization curves are depicted for 40 of 43 mAbs isolated to illustrate the breath of neutralization potency. Curves were obtained from 10 serial dilutions measured in duplicate. (B) The IC50 for each of the isolated mAbs. Error bars represent mean ± SEM. (C) The neutralization curve of mAb 19 with SARS-CoV-2 live virus, Washington USA-WA1/2020 clinical isolate, and SARS-CoV-2 Wuhan Hu-1 spike-pseudotyped virus. Results were obtained from 8 serial dilutions. (D) The linear correlation of IC50 and number of mutations in the VH and VL genes for the 11 most potent mAbs. Analysis was by the simple linear regression followed by Spearman’s r test functions of Prism 9. (E) Neutralization curves of viruses pseudotyped with SARS-CoV-2 Wuhan Hu-1 spike of mAbs 5, 13, 15, and 20 mutated and in germline configuration. Neutralization data curves were analyzed by the nonlinear fit function of Prism 9 and the absolute IC50 was calculated when possible. Data reflect typical plots from at least 2 independent experiments.