Human airway cells prevent SARS-CoV-2 multibasic cleavage site cell culture adaptation

Elife. 2021 Apr 9;10:e66815. doi: 10.7554/eLife.66815.


Virus propagation methods generally use transformed cell lines to grow viruses from clinical specimens, which may force viruses to rapidly adapt to cell culture conditions, a process facilitated by high viral mutation rates. Upon propagation in VeroE6 cells, SARS-CoV-2 may mutate or delete the multibasic cleavage site (MBCS) in the spike protein. Previously, we showed that the MBCS facilitates serine protease-mediated entry into human airway cells (Mykytyn et al., 2021). Here, we report that propagating SARS-CoV-2 on the human airway cell line Calu-3 - that expresses serine proteases - prevents cell culture adaptations in the MBCS and directly adjacent to the MBCS (S686G). Similar results were obtained using a human airway organoid-based culture system for SARS-CoV-2 propagation. Thus, in-depth knowledge on the biology of a virus can be used to establish methods to prevent cell culture adaptation.

Keywords: COVID-19; SARS-CoV-2; airway organoids; cell culture adaptation; furin cleavage site; infectious disease; microbiology; serine proteases; virus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Chlorocebus aethiops
  • Epithelial Cells* / cytology
  • Epithelial Cells* / metabolism
  • Epithelial Cells* / virology
  • Humans
  • Proteolysis
  • Respiratory System / cytology
  • Respiratory System / virology
  • SARS-CoV-2 / physiology*
  • Serine Proteases / metabolism
  • Spike Glycoprotein, Coronavirus / genetics*
  • Virus Cultivation / methods*
  • Virus Internalization*


  • Spike Glycoprotein, Coronavirus
  • spike protein, SARS-CoV-2
  • Serine Proteases