This is a summary, written by members of the CITF Secretariat, of:

Demone J, Maltseva M, Nourimand M, Nasr-Sharif M, Galipeau Y, Alarcon EI, Langlois MA, MacLean AM. Scalable agroinfiltration-based production of SARS-CoV-2 antigens for use in diagnostic assays and subunit vaccines. PLoS One. 2022 Dec 14;17(12):e0277668. doi: 10.1371/journal.pone.0277668. PMID: 36516116; PMCID: PMC9749978.

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

A CITF-funded study published in PLoS One, led by Drs. Marc-André Langlois and Allyson MacLean (University of Ottawa), demonstrated that agroinfiltration, a method to generate proteins in plants, could be used to produce the receptor binding domain (RBD) of the SARS-CoV-2 spike protein. This study is important because these plant proteins can be used to make protein subunit vaccines and serological and neutralization assays. They are low cost, massively scalable, and rapid to develop.

Key takeaways

  • The RBD of the SARS-CoV-2 spike protein produced by agroinfiltration exhibited strong binding to the SARS-CoV-2 receptor ACE 2 (angiotensin-converting enzyme 2), which inhibits the virus’s ability to enter cells.
  • Plant produced RBD also displayed conformations (folding that determines the overall shape of the protein affecting its functions) similar to the protein produced in animal systems.
  • The plant-expressed RBD was readily detected by IgM, IgA, and IgG antibodies from the serum of people with infection and vaccine-induced SARS-CoV-2 antibodies. This means that it was indistinguishable from the viral antigens generated using animal systems.
  • The serum from individuals with infection and vaccine-induced antibodies efficiently neutralized the binding of the plant-expressed RBD to ACE2.

Overall, this study sets the stage for further investigation of the use of cost-effective and massively scalable plant-based viral antigens in protein subunit vaccines, given its comparable properties to its animal cell-expressed counterparts. Such protein antigens have already shown great promise in various research studies and clinical trials.