A University of Central Florida researcher
may have found a defense against the Black Plague, a disease that wiped
out a third of Europe's population in the Middle Ages and which
government agencies perceive as a terrorist threat today.
UCF Professor Henry Daniell and his team have developed a vaccine that
early research shows is highly effective against the plague. Findings of
his National Institutes of Health and USDA funded research appear in the
August edition of Infection and Immunity. The vaccine, which is taken
orally or by injection, was given to rats at UCF and the efficacy was
evaluated by measuring immunity (antibody) developed in their blood.
All untreated rats died within three days while all orally immunized
animals survived this challenge with no 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. It is one of a few labs in
the world authorized to store and work with the highly dangerous agent.
"We are very excited because it appears the oral vaccine is even
more effective than traditional injectable vaccine," Daniell said.
"This could really make a difference."
In the event 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," Daniell said. "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."
The plague had a deadly impact on early Europe, it continues to make
appearances today in places like Africa and Asia. The World Health
Organization reports at least 2,000 cases of the plague annually. The
most recent outbreak in 2005 killed 56 people in the Congo and another
124 were infected before the epidemic was stopped. In the mid 1990s more
than 400 people were infected in India.
Although human trials are still needed, 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. It was the version that ravaged
Europe. If the early findings hold true, this vaccine could mean an
extra layer of protection against natural epidemics and man-made
threats.
The Centers for Disease Control lists the pneumonic plague as a
potential bioterrorism agent because of the speed of which it can be
spread and its 60 percent fatality rate if not treated early enough with
an aggressive array of antibiotics.
Daniell was inspired to investigate an oral vaccine for the plague
because of his pioneering work in diabetes. He and his team genetically
engineered tobacco and lettuce plants with the insulin gene and then
administered freeze-dried plant cells to five-week-old diabetic mice for
eight weeks. By the end of this study, the diabetic mice had normal
blood and urine sugar levels, and their cells were producing normal
levels of insulin.
Daniell figured the same approach might work with a vaccine. 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.
Daniell, who was born and raised in India, has dedicated his life to
finding treatments and cures to diseases that ravage poor countries. He
is conducting research into seven of the top 10 diseases ranked by the
World Health Organization and the Centers for Disease Control, which
remain real issues developing nations.
"I've seen the need. There may be some very expensive treatments
available," Daniell said. "But they are so expensive that developing
countries can't access them. I want to help change that."
Daniell, who is the first UCF Board of Trustee Chair in Life Sciences,
began teaching at UCF in 1998. His research led to the formation of
UCF's first biotechnology company, called Chlorogen, for the commercial
development of patented chloroplast genetic engineering technology. In
2004, he won UCF's Pegasus Professor Award, the top honor given to a
faculty member who excels in teaching, research and service. Daniell
also became only the 14th American in the last 222 years to be elected
to the Italian National Academy of Sciences. In 2007 he was named a
Fellow of the American Association for the Advancement of Sciences.
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