Quantifying absolute neutralization titers against SARS-CoV-2 by a standardized virus neutralization assay allows for cross-cohort comparisons of COVID-19 sera—Oguntuyo 2020

The global COVID-19 pandemic has spurred the development of vaccines and antibody-based therapies, including convalescent plasma therapy, that induce or transfer neutralizing antibodies (nAbs) against the SARS-CoV-2 spike glycoprotein (CoV2-S). However, robust effectiveness testing involves prolonged screening with live virus under difficult BSL3 conditions, limiting high-throughput screening of patient and vaccination sera. Many BSL-2-compatible surrogate viral neutralization assays (VNAs) have been developed to bypass this hurdle. VNAs report results differently, making inter-group comparisons challenging. We created a standardized VNA using VSV-G-based CoV-2-S pseudotyped particles (CoV2pp) that can be generated at scale and generate correct neutralizing titers within 18 hours post-infection. Our standardized CoV2pp VNA correlated well with CoV2-S ELISA and live viral neutralizations in convalescent patient serum. Three separate groups confirmed our standardized CoV2pp VNA (n>120). Our data show that absolute (abs) IC50, IC80, and IC90 values can be legitimately compared across diverse cohorts, highlight the substantial but consistent variability in neutralization potency across these cohorts, and support the use of absIC80 as a more meaningful metric for vaccine or convalescent sera neutralization potency. Finally, we used CoV2pp to screen ultra-permissive 293T clones that stably express ACE2 or ACE2+TMPRSS2. With our CoV2pp, we can generate 150,000 standardized VNA/week.

Oguntuyo, K. Y., Stevens, C. S., Hung, C. T., Ikegame, S., Acklin, J. A., Kowdle, S. S., Carmichael, J. C., Chiu, H. P., Azarm, K. D., Haas, G. D., Amanat, F., Klingler, J., Baine, I., Arinsburg, S., Bandres, J. C., Siddiquey, M. N. A., Schilke, R. M., Woolard, M. D., Zhang, H., COVIDAR Argentina Consortium, … Lee, B. (2020). Quantifying absolute neutralization titers against SARS-CoV-2 by a standardized virus neutralization assay allows for cross-cohort comparisons of COVID-19 sera. medRxiv : the preprint server for health sciences, 2020.08.13.20157222. https://doi.org/10.1101/2020.08.13.20157222