Fig 1. Analysis of plasma responses to SARS-CoV-2 proteins and antibody identification from H2L2 transgenic and BALB/c mice by single cell sequencing.

(A) Schematic diagram of antibody identification from convalescent patients by single cell sequencing. Both Harbour H2L2 transgenic mice and BALB/c mice were immunized with SARS-CoV-2 RBD protein. SARS-CoV-2 RBD protein binding B cells were isolated from enriched mouse spleen and bone marrow cells with beads conjugated with biotinylated SARS-CoV-2 RBD protein. Paired VH and VL of each cell were recovered by single B cell sequencing. The sequences were used for subsequent antibody construction and expression. (B) Antibodies neutralization IC₅₀(y axis) are plotted against SARS-CoV-2 S1 protein binding EC₅₀ (x axis), PR1077, PR953, and PR961 are shown as triangle, and other antibodies are shown as dot. All the data of this figure can be found in the S1 Data file. (C) Heat map shows the relative levels of SARS-CoV-2 S1 binding, hACE2 blocking, and live virus neutralization. The depth of color is proportional to the effect of the antibody (green, S1 binding activity; blue, hACE2 blocking activity; red, neutralizing activity). All the data of this figure can be found in the S2 Data file. (D) Phylogenetic analysis of the relationship between antibody variable gene segments and germline. The relationships between the heavy and light chain variable regions and the germlines from H2L2 transgenic (left) and BALB/c (right) mouse antibodies are shown. hACE2, human angiotensin-converting enzyme 2; RBD, receptor-binding domain; SARS-CoV-2, Severe Acute Respiratory Syndrome Coronavirus 2.