Rapid assessment of SARS-CoV-2-evolved variants using virus-like particles

Science. 2021 Dec 24;374(6575):1626-1632. doi: 10.1126/science.abl6184. Epub 2021 Nov 4.


Efforts to determine why new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants demonstrate improved fitness have been limited to analyzing mutations in the spike (S) protein with the use of S-pseudotyped particles. In this study, we show that SARS-CoV-2 virus-like particles (SC2-VLPs) can package and deliver exogenous transcripts, enabling analysis of mutations within all structural proteins and at multiple steps in the viral life cycle. In SC2-VLPs, four nucleocapsid (N) mutations found universally in more-transmissible variants independently increased messenger RNA delivery and expression ~10-fold, and in a reverse genetics model, the serine-202→arginine (S202R) and arginine-203→methionine (R203M) mutations each produced >50 times as much virus. SC2-VLPs provide a platform for rapid testing of viral variants outside of a biosafety level 3 setting and demonstrate N mutations and particle assembly to be mechanisms that could explain the increased spread of variants, including B.1.617.2 (Delta, which contains the R203M mutation).

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Artificial Virus-Like Particles*
  • Cell Line
  • Coronavirus Envelope Proteins / genetics
  • Coronavirus Envelope Proteins / metabolism
  • Coronavirus Nucleocapsid Proteins / genetics*
  • Coronavirus Nucleocapsid Proteins / metabolism
  • Evolution, Molecular
  • Genome, Viral
  • Humans
  • Mutation*
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism
  • Plasmids
  • RNA, Messenger / genetics
  • SARS-CoV-2 / genetics*
  • SARS-CoV-2 / physiology*
  • Spike Glycoprotein, Coronavirus / genetics
  • Spike Glycoprotein, Coronavirus / metabolism
  • Viral Genome Packaging
  • Viral Matrix Proteins / genetics
  • Viral Matrix Proteins / metabolism
  • Virus Internalization


  • Coronavirus Envelope Proteins
  • Coronavirus Nucleocapsid Proteins
  • Phosphoproteins
  • RNA, Messenger
  • Spike Glycoprotein, Coronavirus
  • Viral Matrix Proteins
  • envelope protein, SARS-CoV-2
  • membrane protein, SARS-CoV-2
  • nucleocapsid phosphoprotein, SARS-CoV-2
  • spike protein, SARS-CoV-2

Supplementary concepts

  • SARS-CoV-2 variants