You wanted green vaccines? You got it!
Henry Daniell works with a variety of plants in his research lab. Photo credit: Jacque Brund.
The team genetically engineered tobacco and lettuce chloroplasts to express the subunits from both cholera toxin and malarial antigens as a dual vaccine against both cholera and malaria. Chloroplasts were used to ensure that the engineered plants could not pass on their new traits via their pollen. The mice were presented (either by injection or orally) with freeze-dried plant cells containing the antigens and then subjected to cholera toxin or to malaria-causing Plasmodium.
Sadly, the untreated mice quickly died. On the other hand, the luckier vaccinated mice acquired immunity that lasted over 300 days (half a normal mouse lifespan).
Clinical trials on humans have not yet begun, but the researchers are optimistic. If this vaccine does prove to be effective in humans, it will be a huge boon. Currently, the only cholera vaccine is extremely expensive and only effective for three years. At present, there is no malaria vaccine.