A rapid and efficient screening system for neutralizing antibodies and its application for SARS-CoV-2

Abstract

After the epidemic of COVID-19, neutralizing antibodies (NAbs) against SARS-CoV-2 has been developed for the preventative and therapeutic purposes. However, few methodologies are reported in detail on how to rapidly and efficiently generate NAbs of interest. Here, we present a strategically optimized screening method for NAbs, which has enabled us to obtain SARS-CoV-2 receptor-binding domain (RBD) specific monoclonal Abs within 4 days, followed by additional 2 days to evaluate their neutralizing activities. Using this method, we obtained 198 specific Abs against SARS-CoV-2 RBD from the blood samples of COVID-19 convalescent patients, and 96 of them showed neutralizing activity. At least 20% of these NAbs exhibited high neutralizing potency. The top 2 NAbs showed the half-maximal inhibitory concentration (IC50) to block authentic SARS-CoV-2 at 9.88 and 11.13 ng/ml, respectively. Altogether, our study provides a fundamental methodology for discovering NAbs with potential preventative and therapeutic value for emerging infectious diseases.

Ultrapotent SARS-CoV-2 neutralizing antibodies with protective efficacy against newly emerged mutational variants

“…The 74 mAbs analyzed in our manuscript were derived from a total of 39 COVID-19 convalescent blood samples collected within a 2-month window post discharge. These 39 convalescent patients have an average age of 45 years old, and majority of them exhibited mild symptoms, as described in the previous study 24 . The original studies to obtain blood samples after written informed consent were previously described and had been approved by the Ethics Board of ChongQing Medical University 24 .…”

“…These 39 convalescent patients have an average age of 45 years old, and majority of them exhibited mild symptoms, as described in the previous study 24 . The original studies to obtain blood samples after written informed consent were previously described and had been approved by the Ethics Board of ChongQing Medical University 24 . Briefly, we utilized SARS-CoV-2 RBD as bait to sort the antigen-specific memory B cells from the COVID-19 convalescent patients.…”

“…By our recently established rapid neutralizing Abs screening system 24 , we have successfully obtained 20 neutralizing Abs with high affinities to SARS-CoV-2 RBD from COVID-19 convalescent individuals, and their neutralizing potencies were confirmed by the half inhibition concentrations (IC 50 s) against authentic SARS-CoV-2 virus quantified via qRT-PCR (Fig. 1a, c and Extended Data Fig.…”