• Authors: Kaku Y. et al.
  • Year: 2021
  • Journal: Cell Rep. 36
  • Applications: in vitro / DNA / FectoCHO Expression System, FectoPRO
  • Cell types:
    1. Name: ExpiCHO-S
      Description: Chinese hamster ovary cells
    2. Name: HEK-293T
      Description: Human embryonic kidney Fibroblast
      Known as: HEK293T, 293T


A pair of heavy and light chain plasmids were transfected into 293T cells using FectoPRO. Two days post transfection, supernatant was used for the screening of Ab reactive to SARS-CoV-2 S. Many Ab were also produced by transient transfection of ExpiCHO cells with the FectoCHO Expression Kit. IgG were purified using a HiTrap rProtein A FF Column.


Administration of convalescent plasma or neutralizing monoclonal antibodies (mAbs) is a potent therapeutic option for coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, SARS-CoV-2 variants with mutations in the spike protein have emerged in many countries. To evaluate the efficacy of neutralizing antibodies induced in convalescent patients against emerging variants, we isolate anti-spike mAbs from two convalescent COVID-19 patients infected with prototypic SARS-CoV-2 by single-cell sorting of immunoglobulin-G-positive (IgG+) memory B cells. Anti-spike antibody induction is robust in these patients, and five mAbs have potent neutralizing activities. The efficacy of most neutralizing mAbs and convalescent plasma samples is maintained against B.1.1.7 and mink cluster 5 variants but is significantly decreased against variants B.1.351 from South Africa and P.1 from Brazil. However, mAbs with a high affinity for the receptor-binding domain remain effective against these neutralization-resistant variants. Rapid spread of these variants significantly impacts antibody-based therapies and vaccine strategies against SARS-CoV-2.