Production of scFv, Fab, and IgG of CR3022 Antibodies Against SARS-CoV-2 Using Silkworm-Baculovirus Expression System

Mol Biotechnol. 2021 Dec;63(12):1223-1234. doi: 10.1007/s12033-021-00373-0. Epub 2021 Jul 25.


COVID-19, caused by SARS-CoV-2, is currently spreading around the world and causing many casualties. Antibodies against such emerging infectious diseases are one of the important tools for basic viral research and the development of diagnostic and therapeutic agents. CR3022 is a monoclonal antibody against the receptor binding domain (RBD) of the spike protein (S protein) of SARS-CoV found in SARS patients, but it was also shown to have strong affinity for that of SARS-CoV-2. In this study, we produced large amounts of three formats of CR3022 antibodies (scFv, Fab and IgG) with high purity using a silkworm-baculovirus expression vector system. Furthermore, SPR measurements showed that the affinity of those silkworm-produced IgG antibodies to S protein was almost the same as that produced in mammalian expression system. These results indicate that the silkworm-baculovirus expression system is an excellent expression system for emerging infectious diseases that require urgent demand for diagnostic agents and therapeutic agents.

Keywords: CR3022 antibody; Fab; IgG; SARS-CoV-2; Silkworm-baculovirus expression vector system; Spike protein; scFv.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / biosynthesis*
  • Antibodies, Monoclonal / genetics
  • Antibodies, Neutralizing / biosynthesis*
  • Antibodies, Neutralizing / genetics
  • Antibodies, Viral / biosynthesis*
  • Antibodies, Viral / genetics
  • Antibody Affinity
  • Baculoviridae / genetics
  • Baculoviridae / immunology
  • Biotechnology
  • Bombyx / genetics
  • Bombyx / immunology
  • COVID-19 / immunology*
  • COVID-19 / virology*
  • Cells, Cultured
  • Gene Expression
  • Hemolymph / immunology
  • Humans
  • Immunoglobulin Fab Fragments / biosynthesis
  • Immunoglobulin Fab Fragments / genetics
  • Immunoglobulin Fragments / biosynthesis
  • Immunoglobulin G / biosynthesis
  • Immunoglobulin G / genetics
  • SARS-CoV-2 / genetics
  • SARS-CoV-2 / immunology*
  • Single-Chain Antibodies / biosynthesis
  • Single-Chain Antibodies / genetics
  • Spike Glycoprotein, Coronavirus / genetics
  • Spike Glycoprotein, Coronavirus / immunology


  • Antibodies, Monoclonal
  • Antibodies, Neutralizing
  • Antibodies, Viral
  • CR3022
  • Immunoglobulin Fab Fragments
  • Immunoglobulin Fragments
  • Immunoglobulin G
  • Single-Chain Antibodies
  • Spike Glycoprotein, Coronavirus
  • immunoglobulin Fv
  • spike protein, SARS-CoV-2