A Covid-19 coronavirus vaccine was made from a tobacco plant – and scientists say it increased the antibodies tenfold.
Clinical studies are now being started around the world, including in Great Britain, following the first successful results.
Scientists say it could address the global shortage of vaccines.
The therapy is unique in that it is obtained from Nicotiana benthamiana, which grows in Australia. It contains nicotine and is used as a stimulant by the indigenous people.
Now the shrub has been genetically modified to fight the coronavirus. It opens the door to mass production of the vaccine on an industrial scale.
It produces a virus-like particle (VLP) that mimics the potentially deadly spike protein that clings to cells.
The external structures are the same, which makes them easily recognized by the immune system. But it is harmless as there is no genetic material to reproduce and spread in the body.
The 180 Canadian participants, ages 18 to 55, received two doses of the vaccine called CoVLP three weeks apart. After six weeks, they produced up to ten times higher neutralizing antibodies than in recovering patients.
It worked best when paired with a chemical cocktail used in routine flu medication known as AS03.
The corresponding author Dr. Brian Ward of the Quebec City biopharmaceutical company Medicago said, “The plant-derived vaccine candidate was well tolerated and triggered an immune response.”
It can’t cause infection, but it still teaches the body to fight it – which leads to immunity.
Dr. Ward said, “Multiple Covid vaccines are used, but global demand far exceeds supply and different formulations may be required for certain populations.”
All formulations were well tolerated, with side effects of short duration and mild to moderate.
Dr. Ward said more than 130 million people were infected with Covid – and there were over 2.8 million deaths.
He continued, “Although significant advances have been made in patient care, current treatment options remain relatively limited.
“No single vaccine can be made in sufficient quantities to meet global needs quickly enough, and different populations and environments may require different formulations.”
Dr. Ward added, “One such formulation is CoVLP, a virus-like particle vaccine candidate that contains the SARS-CoV-2 spike protein produced in the Nicotiana benthamiana plant.”
The original volunteers are followed for 12 months. A two-dose regimen of CoVLP with AS03 has entered major Phase 2 and trials in Canada, the UK, Brazil and the US.
Similar projects are also planned for other countries in Europe and Latin America – there the cases are increasing.
Dr. Bruce Clark, President and CEO of Medicago, said, “Establishing an adequate supply of Covid-19 vaccines within the next year is a challenge that requires multiple approaches using different technologies.
“Our proven plant-based technology can provide a collective solution to this public health emergency.”
Making VLP vaccines in plants is a complex process, but it only takes six to eight weeks – much faster than the six months in a hen’s egg.
It also removes ethical concerns about dependence on animal products.
The scientists genetically engineered a special plant-infiltrating bacterium called Agrobacterium to turn the nicotine plants into miniature VLP “factories”.
Specific sequences of viral DNA that produce the external structural proteins of the coronavirus are inserted into its genome. Then Agrobacterium is allowed to infect the plant.
Once in the cells, the genetically modified Agrobacterium delivers the inserted viral DNA to the plant – so it can be used as a template for the production of the virus-like particle.
As soon as the plant is infected with the Agrobacterium, it reliably produces the virus-like particles. All that is left is to harvest the plant and clean the VLPs from their tissues.
The study was published in the renowned British journal Nature Medicine.