Canada approves plant-based COVID-19 vax

Health Canada has granted authorization for Covifenz, a plant-based COVID-19 vaccine developed by Medicago and GlaxoSmithKline (GSK).

Covifenz is made up of plant-based virus-like particles (VLP) and aims to prevent COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in individuals between the ages of 18 to 64 years old.

Medicago uses its Proficia technology to synthesize the virus’ code once a virus has been genetically sequenced. In doing so, the firm claims its genetic instructions can then be “read” by plants.

“In the plant-based vaccine development process, living plants are used as bioreactors to produce a non-infectious VLP that mimics the target virus,” Brian Ward, medical officer at Medicago told BioProcess Insider.

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The Proficia technology uses Nicotiana benthamiana plants, which according Medicago is the most widely used experimental host in plant virology, because of the large number of viruses that can successfully infect it. Therefore, the natural cell process of Nicotiana benthamiana is provisionally exploited to produce VLPs.

Ward told us that a pivotal aspect for the development of its plant-based vaccine “is centered on our greenhouses.” After the synthesis process has taken place, the code is inserted into a bacterial vector, and they submerge plants into a bacterial bath. Then, using a vacuum, the air inside the plants’ intercellular space is removed and liquid is absorbed by the plants.

The plants will start producing VLPs and are put into a controlled greenhouse for a minimum of four days to quickly produce large quantities of VLPs. After this, the plants are harvested and VLPs are extracted. The plant leaves will then be blended into a solution to extra the VLPs. And finally, the particles are purified and tested for sterility and quality.

The vaccine also uses GSK’s pandemic adjuvant system after the pair teamed up to develop the vaccine in July 2020. GSK claims that the use of an adjuvant can be important in a pandemic situation as it could potentially boost the immune response and decrease the amount of antigen required per dose, meaning larger amounts of vaccines can be produced.

Plant advantage

Though Ward would not compare Covifenz to other available COVID-19 vaccines as Medicago “didn’t perform head-to-head comparison,” he did list the following as advantages of plant-based vaccines:

The Canadian government has a contract with Quebec-based firm Medicago to supply the COVID-19 vaccine, which the firm says it is committed to fulfilling as soon as possible.

Additionally, Health Canada said its decision to authorize Covifenz is based on scientific data that Medicago submitted as part of its rolling submission that begin in April 2021.