This new COVID vaccine uses plants as a factory for viral proteins

Last week, Canadian biotechnology company Medicago and UK pharmaceutical company GlaxoSmithKline announced the successful results of a phase III vaccine trial with a twist. This COVID vaccine is made from plants.

This vaccine uses what are called “virus-like particles,” which are essentially the outer shell of the SARS-CoV-2 virus, to elicit an immune response. According to the technique, this technique was also very effective in preventing the disease against delta variants and some antigenic strains. Outline of the trial.. However, this test was conducted before the Omicron variant became widespread.

Like many other successful vaccines on the market, the idea is to build the SARS-CoV-2 protein. Without it The virus itself. This allows the immune system to be trained to recognize intruders without repelling them. RNA vaccines utilize the cellular mechanisms of the human body to build these proteins. Instead, in this vaccine, the plant does the protein-building work.

In a phase III study, a study of 24,000 people found that the vaccine was 75% effective in blocking symptomatic treatment for delta variants, according to a Medicago press release. The full results have not yet been published in a peer-reviewed journal. Although its efficacy numbers are lower than the initial efficacy reported by Pfizer and Moderna, the mRNA vaccine has only been tested against strains of the COVID-19 ancestry. Although the estimates are widespread, the mRNA vaccine appears to be approximately 80 percent effective against delta symptomatic disease.

Mark Andre Dorst, vice president of research and innovation at Medicago, warns that researchers are still unable to determine efficacy figures due to the very few cases of severe illness recorded in this study. No one vaccinated with the Medicago vaccine had a severe COVID.

The manufacturing process begins with Agrobacterium, a bacterium that has the ability to transfer DNA to plant cells, “says D’Aoust. Vaccine developers insert the gene sequence that encodes the COVID spike protein into these bacteria and make soups with modified microorganisms. Then it sucks air from the leaves of the plant and soaks the plant in the soup. This tobacco-like plant has a weak immune system and is susceptible to infection.

The leaves absorb the bacteria and instruct the plant cells to make the spike proteins that the coronavirus uses to latch into human cells. “Within a day of contacting the plant with Agrobacterium, the DNA is transferred and the cells begin to produce antigen,” says D’Aoust.

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Spike is not an exact replica of SARS-CoV-2. They are edited so that they cannot easily enter human cells, so they are more likely to hang out where the human immune system can find them.

These individual proteins are spiked into a bristle sphere and then extruded from the plant cell membrane, reflecting how SARS-CoV-2 particles regenerate in human cells. The main difference is that virus-like particles lack genetic material and internal proteins that allow complete viral replication.

“Virus-like particles have this beauty of displaying antigens just like viruses,” says D’Aoust. It is shaped like a virus and has the right protein. “And all these features are well recognized by the immune system, but when viewed from the inside, they are empty.”

After about a week, the plant accumulated enough material to harvest around the cell membrane. Medicago refines the harvested particles to make the raw material for the vaccine. They are added to a set of other ingredients manufactured by GSK that enhance the immune response to the particles.

This technology is decades old and is used in the HPV vaccine Gardasil and some hepatitis A vaccines. Medicago is also working on a flu vaccine of the same technology.

A major innovation here is that Amin Kamen, a professor of bioengineering at McGill University in Canada and studying virus-like particles, is a plant. “Traditionally, we use microbial fermentation to make vaccines,” says other expensive biological reactions.The WHO is a plant-based vaccine Large-scale manufacturing and adaptation may be cheaper. But purifying particles from plants is “not a trivial matter,” says Kamen.

“I think there is great potential if we succeed,” says Kamen.

He also states that SARS-CoV-2 is particularly suitable for this technique, as it may be shaped to be very stable on the outer peplomer.

This stability facilitates the storage of virus-like particle vaccines. According to Medicago, vaccines can be kept at refrigerator-level temperatures, which can speed up delivery to areas with little medical infrastructure. “At least we’re serious about making it accessible,” says Kamen. “Yes, I think we are facing a current pandemic, but the value is that we are building the capacity for a future pandemic.”

Medicago plans to submit final data to Canadian regulators by the end of the year, D’Aoust said. We have started the submission process to the Food and Drug Administration.