Woking with his colleagues, Professor Henry Daniell, who was born and raised in India, had developed this vaccine, which is taken orally or by injection. It was given to rats at UCF and the efficacy was evaluated by measuring immunity (antibody) developed in their blood.
All the rats that remained untreated died within three days while all orally immunized animals survived without any traces of the plague in their bodies.
The rats were exposed to a heavy dose of Yersinia Pestis bacteria, which causes the plague, at the U.S. Army Medical Research Institute of Infectious Diseases in Maryland.
"We are very excited because it appears the oral vaccine is even more effective than traditional injectable vaccine. This could really make a difference," said Daniell.
In case of a bioterror attack, the oral form makes the vaccine practical, as the distribution of pills would be much quicker and likely more effective because no special skills or sterile needles are needed to administer them.
"It worked beautifully. It's expensive to create an injectible vaccine. But with oral vaccines, it is quite cheap. You grow your plants and then you convert them into capsules," said Daniell.
While there's still a need for human trials, Daniell is confident the vaccine will work for the bubonic and pneumonic plague based on animal studies.
Pneumonic plague is spread through the air. Without treatment a person can die within days. Bubonic plague is the more common form and is transmitted through fleabites and kills about 70 percent of those infected within 4-7 days if not treated.
In case the early findings show positive results, this vaccine could mean an extra layer of protection against natural epidemics and man-made threats.
For this study, he genetically engineered plant cells with a protein found on the outside of Yersinia pestis. The vaccine was inside the plant cells, which were given to the rats.
The vaccine was protected from digestion in the stomach and was then absorbed in the gut. It kick started the immune system into producing antibodies, which protects against the deadly disease. Three to five doses seem to do the trick.
The findings of this study appear in the August edition of Infection and Immunity.