U of O Scientist Seeking Edible Vaccine for COVID-19 Hopes to Put Them in Veggies that People Would Eat

 

Posted by Erin Elizabeth

University of Ottawa professor and plant biologist Allyson MacLean hopes that eating your veggies will one day soon protect you against COVID-19.

McClean has been busy during the pandemic designing an edible vaccine for the virus. Her research involves injecting tomato, potato, and lettuce plants with a tiny particle of viral DNA swimming in a bacterial solution. McClean, an assistant professor of plant biology, said:

“We take a syringe that does not have a needle point. You press it up against the large leaf … and you basically push … the bacteria into the plant tissues.” 

The bacteria carry that DNA into the plant, which triggers the production of viral proteins. Consuming the plant enables these proteins to pass through the digestive system, where they’re taken up by specialized cells in the gut, stimulating a type of immunity called “mucosal immunity.” It’s of particular interest to the scientists in battle with COVID-19 because the virus that causes the disease (SARS-CoV-2) enters the body via the respiratory system’s mucosal surface. 

In her current research to create an edible vaccine for COVID-19, MacLean uses “parts of the virus that other researchers believe will elicit a strong protective antibody response.” They’re hitching a ride into the plant tissue on the back of her old friend Agrobacterium.

MacLean has spent a decade studying symbiosis in nature, specifically how microbes and plants co-exist. One of the most common microbes is Agrobacterium tumefaciens, which lives in soil and naturally latches onto plants. She explained:

“It finds a wound in the plant and it gets in there. It takes part of its DNA and injects it into a plant cell. It basically makes the plant cells grow tumours … that the bacteria can then use as a food source.” 

“People realized a few decades ago that this was going on in nature,” she said. “Somebody had the brilliant idea: OK, can we harness this as a way of making genetically modified organisms?”

MacLean is currently using a close relative of tobacco to determine the best way to make a plant express the viral proteins. Next stop, lettuce. 

The pandemic has challenged MacLean’s research. When COVID-19 struck in March, she struggled to move her hands-on laboratory course online. She was especially worried about her “precious transgenic mutant plants” left behind in the lab when the U of O campus closed down due to COVID-19. To continue caring for them, she was granted permission to feed and fertilize the plants three times a week. 

MacLean thinks injecting plants with vaccines is a more efficient route to global immunity. She also believes that more people would rather eat their medicine that get a shot, adding:

“Plant-based vaccines are better for the developing world. They’re cheaper to produce. They don’t need … to be refrigerated for long periods of time.”

“People are more willing to ingest a vaccine than they are to get a needle.” 

In collaboration with John Bell of the Ottawa Health Research Institute, MacLean’s work will be tested on mice. She said:

“This project is pairing up a cancer researcher who uses viruses to tackle cancer and a plant biologist who normally studies the way microorganisms interact with plants. We’re both stretching out of our comfort zones.”

 

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