Erythro-VLPs: Anchoring SARS-CoV-2 spike proteins in erythrocyte liposomes

PLoS One. 2022 Mar 11;17(3):e0263671. doi: 10.1371/journal.pone.0263671. eCollection 2022.


Novel therapeutic strategies are needed to control the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) pandemic. Here, we present a protocol to anchor the SARS-CoV-2 spike (S-)protein in the cytoplasmic membranes of erythrocyte liposomes. A surfactant was used to stabilize the S-protein's structure in the aqueous environment before insertion and to facilitate reconstitution of the S-proteins in the erythrocyte membranes. The insertion process was studied using coarse grained Molecular Dynamics (MD) simulations. Liposome formation and S-protein anchoring was studied by dynamic light scattering (DLS), ELV-protein co-sedimentation assays, fluorescent microcopy and cryo-TEM. The Erythro-VLPs (erythrocyte based virus like particles) have a well defined size of ∼200 nm and an average protein density on the outer membrane of up to ∼300 proteins/μm2. The correct insertion and functional conformation of the S-proteins was verified by dose-dependent binding to ACE-2 (angiotensin converting enzyme 2) in biolayer interferometry (BLI) assays. Seroconversion was observed in a pilot mouse trial after 14 days when administered intravenously, based on enzyme-linked immunosorbent assays (ELISA). This red blood cell based platform can open novel possibilities for therapeutics for the coronavirus disease (COVID-19) including variants, and other viruses in the future.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COVID-19 Vaccines* / chemistry
  • COVID-19 Vaccines* / immunology
  • COVID-19 Vaccines* / pharmacology
  • COVID-19* / immunology
  • COVID-19* / prevention & control
  • Erythrocyte Membrane* / chemistry
  • Erythrocyte Membrane* / immunology
  • Female
  • Liposomes
  • Mice
  • Molecular Dynamics Simulation*
  • Pilot Projects
  • Protein Domains
  • SARS-CoV-2 / immunology*
  • Spike Glycoprotein, Coronavirus* / chemistry
  • Spike Glycoprotein, Coronavirus* / immunology
  • Spike Glycoprotein, Coronavirus* / pharmacology
  • Vaccines, Virus-Like Particle* / chemistry
  • Vaccines, Virus-Like Particle* / immunology
  • Vaccines, Virus-Like Particle* / pharmacology


  • COVID-19 Vaccines
  • Liposomes
  • Spike Glycoprotein, Coronavirus
  • Vaccines, Virus-Like Particle
  • spike protein, SARS-CoV-2

Grants and funding

This research was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC, RGPIN-2021-03926), the Canada Foundation for Innovation (CFI) and the Ontario Ministry of Economic Development and Innovation. M.C.R. is the recipient of an Early Researcher Award of the Province of Ontario and a University Scholar of McMaster University. Cryo-EM images were collected at the Facility for Electron Microscopy Research (FEMR) at McGill University. FEMR is supported by the Canadian Foundation for Innovation, the Quebec government, and McGill University. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.