A Canadian biopharmaceutical company called Medicago have developed a COVID-19 vaccine from materials produced in Nicotiana benthamiana, a relative of tobacco. This smoking hot study found that two doses of the vaccine generated around ten times more neutralizing antibodies than seen in patients recovering from viral infection, whilst adverse effects of the vaccine were said to be “primarily mild or moderate and of transient duration”. Subsequently, Canadian health regulators have started a rolling review of the vaccine; a decision met with delight by Medicago’s Chief Operating Officer, Carolyn Finkle, who said “Health Canada’s decision to accept for review the IO rolling submission for Medicago’s vaccine, the first Canadian-based COVID-19 vaccine submission, meets an important milestone”. This plant-powered vaccine will soon be coming to our shores as part of Medicago’s phase 3 trials, as they recently received regulatory approval to launch phase 3 of their clinical development in the UK, as well as in Canada, the US and Brazil.
The Medicago vaccine contains particles called Coronavirus-like particles (CoVLP), which are able to self-assemble in the plant and display SARS-CoV-2 proteins in the lipid bilayer. These VLPs closely mimic the native structure of the COVID-19 virus, and therefore cause an immune response when injected into patients, however, are not infectious as they lack the virus’ genetic material. To extract the CoVLPs from plant tissue, the leaves are first blended (to form the ultimate superfood smoothie), before CoVLPs are purified. From here, the purified CoVLPs are mixed with GSK’s pandemic adjuvant to form the final vaccine; two doses of which are administered 21 days apart.
The advent of a plant-produced vaccine may mean we are able to leaf COVID-19, lockdowns, and social distancing behind sooner than anticipated, as this new vaccine offers advantages unseen in current treatments. The Medicago vaccine stimulated a cellular immune response of the T helper-2 type, producing interferon-γ and interleukin-4 which act as key players in the immune response and are not produced in response to other vaccines. Plant-produced vaccines can also be scaled up much faster than the current vaccines have been, and can be stored at higher temperatures (between 2 and 8ᵒC) meaning they may be useful in varied environments.
This plant-powered jab may be some way from being in the arms of people around the world, however the pioneering work of this Canadian team has shown how versatile plants can be, as not only can they fill our stomachs, bottles, and pipes, but they can now also protect us from one of the deadliest viruses we have seen in generations.