Two scientists have revived the process of making plant-made vaccines in an effort to lower costs and to tailor treatment to individual needs.
Hugues Fausther Bovendo, Canda, and Gary Kobinger, USA, advocate’molecular agriculture’, which inserts DNA into plants cells to create proteins.
To make a vaccine, the cell is transformed into an extract.
Because it is cheaper than bioreactor suites, Molecular farming was originally proposed in 1986 as an alternative to biomanufacturing.
In phase 3 clinical trials, this method was successful for CoVLP, a COVID-19 vaccine candidate, and a vaccine to fight influenza. Both of these would be administered orally, not as shots.
‘The plant-made vaccines against influenza virus and SARS-CoV-2 are expected to be the first therapeutic proteins produced in whole plants for human use,’ Fausther-Bovendo and Kobinger wrote in an article published in Science Magazine.
The glucocerebrosidase enzyme is an injectable drug that’s produced from taliglucerasealfa, which treats Gaucher disease. It’s produced in a carrot culture, rather than in real plants.
According to the Centers for Disease Control and Preventions (CDC), the most common method for making flu vaccines is using an egg-based manufacturing process – a method that has been used for more than 70 years.
Injectable candidate vaccine viruses (CVVs), are placed into fertilized eggs of chicken and left to incubate for several days.
The virus fluid is taken from eggs to make the vaccine injectable.
Fausther–Bovendo, Kobinger and others repeatedly mentioned the high cost of the traditional approach in Science Magazine. However, they also noted that plant-produced protein gives a stronger immune response because they can be taken orally.
The team highlighted the clinical trials of traditional and plant-made vaccines for E.coli, hepatitis B, rabies Lyssavirus and norovirus that were conducted between 1998 and 2004.
Scientists wrote that the percentage of individuals who developed an immune response against the target in these clinical trials was lower than in clinical trials using standard vaccines administered via parenteral route.
“The yield of recombinant protein produced in plants has increased substantially since then, suggesting that new edible plant vaccines could now produce meaningful immune responses.
Fausther Bovendo and Kobinger explain that plant-made therapies can also be given orally. They may not require much processing and thus avoid costly and time-consuming steps.
The authors also note that edible vaccines are still in preclinical development.
New edible plant-made vaccines are more effective than proof-of-concept vaccines that were tested decades ago and generated weak immune responses.
Fausther Bovendo and Kobinger share their views on the article, which explains that therapeutic doses are higher than those for vaccines. Therefore, it is important to invest in manufacturing infrastructure to enable large-scale production of plant therapeutic products.
Medicago, a Canadian biopharmaceutical company, has announced that it is testing a two-dose COVID-19 vaccine. It uses tobacco to create coronavirus-like particles.
It is made from a tobacco plant variety and contains virus-like particles (VLPs).
VLPs are molecules that closely resemble native viruses but are not infectious as they don’t contain any genetic material. They are added to the soil and absorbed into the plant as it grows.