Contributed by guest blogger: Nicole Engelhardt ’11
Usually when you get a vaccine it means you get a needle and a bandage. Not only that, but you get an attenuated virus. These weakened virus particles are strikingly similar to viable ones; they even infect cells. Because of their weakened state, they infect slower than natural virus particles, giving the body time to react. However, people who have weakened immune systems can still exhibit symptoms as if they were infected by the natural virus.
But a new tool may make this issue obsolete. What really matters when it comes to a vaccine is the shape of the particle, not the contents. The shape is recognized by B-cells in the body which then reproduce creating antibodies that attack all of the virus particles. However, these B-cells are very specific and very picky. Normally, it makes sense to use a weakened virus because it has the exact same shape as a normal virus and your B-cells will react to the vaccine as if it were the real thing. Is there any way, then, to produce the exact shape of the virus and therefore the correct antibodies without having the harmful side effects?
This paper explores the rotavirus particle which is the leading cause of gastroenteritis in the world. In some parts of the world, gastroenteritis can be deadly for many children. As it happens, the shape of the rotavirus particle can be mimicked almost exactly in plants. The shape of this virus is a capsid made out of proteins. First, the authors take the genes that code for the capsid proteins and insert it into the genome of the plants. Then the plants express the viral genes, creating the virus capsid proteins inside the cells of the plants. More incredible than that, these proteins self-assemble into the exact shape of the rotavirus capsid. Now you have a plant containing just the shell of the virus!
The experiments are still in their early stages, but when mice were fed these plants, the authors found they were producing the same antibodies that are produced when mice are actually infected with rotavirus. This bodes well for future research in humans. Once the antibodies are created, the severity of future infections is greatly decreased. If these transgenic plants do work, it could mean a safer and perhaps more affordable form of the vaccine that could help people the world over fight rotavirus before it can infect.
How would eating a vaccine affect the dosage? Would a large amount of the plant need to be ingested in order to get a dosage of the viral particles large enough to elicit an immune response?
Does anyone know if this technique has been done with other viruses in attempt to create edible vaccines? I had never heard of this before. It sounds pretty exciting.
I was wondering the same thing…
Also, the authors briefly mention cost but it would be interesting to know if using plants would result in a more cost-effective vaccine.
Did the paper mention anything about the possibility of using this method with other kinds of viruses or does it work specifically with rotavirus?
Is the idea behind the plant just so that it’s an edible vaccine, or do the particles assemble and keep better if the genes are expressed by the plant than they would if the proteins were thrown together in a test tube?
Oooh Im the first to comment! A very interesting approach to generating vaccines. I wonder how long the viral particles are stable in the plant. For example, could the plant be dried and still be immunogenic? Imagine the public health benefits of a vaccine that could be transported and stored as easily as dried leaves! No more carrying fridges to remote parts of Africa.