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New
Campylobacter vaccine for poultry // 08 Oct 2008 Source of Article: http://www.worldpoultry.net/news/id2205-61603/new_campylobacter_vaccine_for_poultry.html A new poultry vaccine in development at the
Trials have shown that the vaccine
significantly reduced the pathogen's ability to colonise
young chickens' intestines, where the infection begins. The goal is to halt
the contamination before it spreads and survives on raw chicken sold in
stores. "Chickens don't actually cause the
disease, nor does it make them ill. It's the organism they carry that makes
people sick," said Lynn Joens, a professor in
The University of Arizona Dept of Veterinary Science and Microbiology. Funded by the USDA, Joens
and UA graduate students started analysing
Campylobacter's infection process about 4 years ago, looking for a way to
interrupt it. The laboratory team discovered that the pathogen first attached
itself to the surface of the chick's intestines and then began to multiply.
Attacking the "sticking" mechanism seemed to be the key. When the UA researchers sequenced the
intestinal surface protein they identified the gene responsible for producing
Campylobacter’s adherence protein. Then they built a trial vaccine around it
using Salmonella bacteria as a vector. The adherence gene was inserted into
Salmonella bacteria, which is nonpathogenic for poultry. The resulting live
vaccine – containing Salmonella programmed to make the Campylobacter adhering
protein – was fed to young chickens to protect them. “Once the Salmonella in the vaccine
produced the Campylobacter protein, the chicks made antibodies against it in
their intestines,” Joens says. "In our first
study of 15 birds we got a very significant reduction – 98% – in
Campylobacter infection, compared with a control group. We're now repeating
the trial on a larger scale." Joens'
preliminary figures show that 270 million Campylobacter organisms were
present in non-vaccinated birds, compared with 67,000 organisms in the
vaccinated birds. "You need at least 500 organisms to
produce disease in humans," he explained. "The chlorine in the
packinghouse chillers usually reduces numbers of bacteria by 1,000 to 100,000
organisms, so the chickens should be free of Campylobacter after
processing." The UA group was the first to discover the
adherence protein, which is only produced when Campylobacter jejuni colonizes certain surfaces, like chicken intestine
and skin. They have a patent pending in both the "If everything goes right we could
have a commercial vaccine in 3-5 years," Joens
said. Source: |
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