Efficient production of recombinant SARS-CoV-2 spike protein using the baculovirus-silkworm system

Biochem Biophys Res Commun. 2020 Aug 20;529(2):257-262. doi: 10.1016/j.bbrc.2020.06.020. Epub 2020 Jun 9.


In the case of a new viral disease outbreak, an immediate development of virus detection kits and vaccines is required. For COVID-19, we established a rapid production procedure for SARS-CoV-2 spike protein (S protein) by using the baculovirus-silkworm expression system. The baculovirus vector-derived S proteins were successfully secreted to silkworm serum, whereas those formed insoluble structure in the larval fat body and the pupal cells. The ectodomain of S protein with the native sequence was cleaved by the host furin-protease, resulting in less recombinant protein production. The S protein modified in furin protease-target site was efficiently secreted to silkworm serum and was purified as oligomers, which showed immunoreactivity for anti-SARS-CoV-2 S2 antibody. By using the direct transfection of recombinant bacmid to silkworms, we achieved the efficient production of SARS-CoV-2 S protein as fetal bovine serum (FBS)-free system. The resultant purified S protein would be useful tools for the development of immunodetection kits, antigen for immunization for immunoglobulin production, and vaccines.

Keywords: SARS-CoV-2; Silkworm-BmNPV expression system; Spike protein.

MeSH terms

  • Animals
  • Bombyx / cytology*
  • Bombyx / enzymology
  • Bombyx / virology*
  • Cell Line
  • Cloning, Molecular
  • Furin / metabolism
  • Nucleopolyhedroviruses / genetics*
  • Nucleopolyhedroviruses / metabolism
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / genetics
  • Spike Glycoprotein, Coronavirus / biosynthesis*
  • Spike Glycoprotein, Coronavirus / chemistry
  • Spike Glycoprotein, Coronavirus / genetics
  • Spike Glycoprotein, Coronavirus / isolation & purification*


  • Recombinant Proteins
  • Spike Glycoprotein, Coronavirus
  • spike protein, SARS-CoV-2
  • Furin