Vaccine hesitancy remains a challenge worldwide, but a innovative plant-produced COVID-19 vaccine from Quebec's Medicago could shift perspectives.
In countries like France, Germany, and Canada, many individuals continue to hesitate on vaccination due to concerns over mRNA vaccines and potential side effects. Even with traditional vaccine options available, uptake lags. A January 26, 2022, medRxiv prepublication highlights a novel approach from Medicago researchers, who produce the vaccine using plants.
This method avoids live virus handling by using only the genetic sequence. The key plant is Nicotiana benthamiana (see photo), a tobacco relative native to Australia and often viewed as a weed. It excels at yielding recombinant proteins.
Plants are grown in greenhouses, then infiltrated using Agrobacterium tumefaciens, a bacterium that transfers genetic material into plant cells. Researchers insert a plasmid with the SARS-CoV-2 Spike protein gene into the bacteria. Plants are submerged in tanks under vacuum to draw out leaf air, allowing absorption of the bacterial solution. This tricks the plant's cells into producing the protein.
The plant identifies and degrades the foreign material, while researchers harvest and purify virus-like particles from leaf buds. These particles mimic the virus with Spike proteins but lack genetic material, rendering them non-infectious. Enzymes then digest the plant cell walls to release the particles after harvest.
This technique, refined over three decades, has produced vaccines for hepatitis B and HPV. Its advantages include direct delivery of Spike proteins—bypassing human cell production—rapid one-week timelines, on-demand scalability, and proven efficacy against multiple coronavirus variants. Medicago aims for swift authorization and large-scale production.
