A Vaccine to Prevent Food Poisoning?
May 24, 2004 -- Imagine taking a pill or eating a piece of
fruit and not having to worry about food poisoning for weeks at a time.
Researchers say they're making strides toward developing a
number of vaccines that may offer protection against some of the most common
causes of food-borne illness.
Preliminary tests of two new experimental vaccines show they're
effective in protecting against infection with several types of dangerous
bacteria found in food, including:
Salmonella -- a bacteria often found in raw poultry and eggs
Listeria -- a bacteria often found in improperly pasteurized
milk or cheese
E. coli -- a potentially deadly bacteria spread through
contact with human or animal feces or contaminated water or food. Most illness
has been associated with eating undercooked, contaminated ground beef.
"Vaccines have been proven to be an effective means of
prevention for many infectious diseases, but there are no effective vaccines
for most common food-borne diseases," says researcher John Gunn of the Ohio
State University, in a news release. "The development of a single vaccine
that provides protection against the most common food-borne pathogens would
greatly enhance human health and well-being worldwide."
Results of the studies were presented today at the 104th
General Meeting of the American Society for Microbiology in New Orleans.
Vaccines Designed to Fight Bacteria in Food
In the first study, researchers modified a crippled strain of
salmonella bacteria and combined it with genes from another common food-borne
bacterium, listeria, in order to stimulate immunity to both types of
When they gave the oral vaccine to mice, it protected them 100%
against lethal does of both bacteria. Researchers say the vaccine appeared to
protect the mice for up to six weeks after vaccination.
In the second study, researchers reported success toward the
development of a vaccine against one of the most dangerous forms of bacteria,
E. coli O157:H7. These bacteria secrete a toxin that causes mild to
bloody diarrhea, and in some cases infection may lead to kidney failure, brain
damage, or death.
Researchers transferred a modified version of the toxin genes
into tobacco plants and created a plant-derived vaccine. When given to mice,
this vaccine stimulated the production of antibodies against the toxins.
"Next, the immunized mice will be challenged with the toxin
or toxin-producing bacteria to determine if the plant vaccine is
protective," says researcher Sharon Wen of the Uniformed Services
University of the Health Sciences, in the release. "Once the protective
efficacy of these plant-based vaccines is established, the bacterial genes can
then be moved into other plants such as bananas or corn for delivery to humans