Single-Cell Sequencing Identifies Effective SARS-CoV-2 Antibodies in Recovered Patients
The authors isolated 14 powerful antibodies from 8,558 antigen-binding IgG1+ clonotypes using single cell BCR sequencing. The most effective one is BD-368-2, with an IC50 against pseudotyped and real SARS-CoV-2 of 1.2 and 15 ng/mL, respectively. Additionally, BD-368-2 showed significant therapeutic and preventative effects on mice infected with SARS-CoV-2. The authors also showed that SARS-CoV-2-neutralizing antibodies may be chosen directly based on how closely their anticipated CDR3H structures matched those of SARS-CoV-neutralizing antibodies. Overall, they demonstrated that high-throughput single cell BCR sequencing is effective in discovering human-neutralizing antibodies in response to pandemic infectious illnesses.
Fig.1 Graphical abstract. (Cao, 2020)
Research Criteria
They select 14 powerful neutralizing antibodies from 8,558 antigen-binding IgG1+ clonotypes using single cell immunological profiling. And they discovered BD-368-2, the most effective mAb. In vivo tests showed that BD-368-2 could offer significant therapeutic efficacy and preventative defense against SASR-CoV-2.
Fig.2 Experimental design. (Cao, 2020)
Sample Type
B cells isolated from human PBMCs.
Result—High-Throughput Sequencing of Single B Cells from Convalescent Patients
They used a 10x Chromium technology to perform single cell RNA (scRNA) and single cell BCR sequencing on newly isolated B cells or CD27+ memory B cell fractions. They discovered that the selected CD27+ memory B cells significantly increased the number of sequenced memory B cells and identified IgG1 clonotypes, and that single cell BCR data revealed the enrichment of IgG1 clonotype. Only one of the 130 in vitro-expressed mAbs chosen from enriched memory B cells in IgG1+ clonotypes demonstrated a modest capacity to neutralize both pseudotyped and true SARS-CoV-2. Since RBD-binding mAbs and neutralizing mAbs have low efficacy, the antigen-affinity-based selection is essential, which may considerably enrich the RBD-binding B cells.
Fig.3 Summary of the 10x scRNA-seq and scBCR-seq of 12 convalescent patients' B cells. (Cao, 2020)
Result—Selecting Potent Neutralizing mAbs Based on the Structural Similarity of CDR3H
The authors compared the anticipated structure of each IgG1-presenting clonotype based on CDR3H to the crystal structure of antibodies available in the PDB database. The discovered antibodies' CDR3H sequences were highly similar to m396, an antibody neutralizing SARS-CoV-2 by inhibiting ACE2-RBD binding. Surprisingly, the authors discovered that 7 of the 12 antibodies had a high RBD-binding affinity as well as a robust neutralizing ability against pseudotyped SARS-Cov-2. Furthermore, the heavy chain was largely encoded by VH3-66/JH6 or VH3-53/JH6, and the light chain by VLK1-9 or VLK1D-33/39.
Fig.4 Characteristics of the neutralizing antibodies identified based on CDR3H structural. (Cao, 2020)
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The adaptive immune system is dependent on the wide range of B-cell receptors (BCR) and T-cell receptors (TCR) resulting from the recombination of the variable (V), diversity (D), and joining (J) loci. To define the full repertoire, our single cell TCR/BCR profiling service employs tailored bioinformatics and ultra-deep sequencing of V(D)J regions. Recent microfluidic technology enables single-cell BCR and TCR chain pairing.
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Reference
- Cao, Y.; et al. Potent neutralizing antibodies against SARS-CoV-2 identified by high-throughput single-cell sequencing of convalescent patients' B cells. Cell. 2020, 182(1): 73-84.
