US scientists claim FMD vaccine breakthrough

Beef Central, 06/07/2012

Scientists in the United States have produced a molecular vaccine against a strain of Foot and Mouth Disease in a breakthrough they have described as the “biggest news in FMD research in the last 50 years”.

The research at the Plum Island Animal Disease Centre on Long Island has focused on the production of a molecular vaccine that will enable scientists to accurately differentiate between vaccinated and infected animals, should a future outbreak of the disease strain occur in the US.

They say the development will reduce the requirement to destroy all animals in a herd when just a few become infected.

A report explaining the development on science website Science Daily said traditional vaccines for Foot and Mouth Disease typically had three major problems.

“First, there are so many different strains of the FMD virus that you must have a very well-matched vaccine to have any effect; second, traditional vaccines contain live FMD virus so they cannot be produced in the United States, and; third, depending on a vaccine's quality, it can be nearly impossible to determine whether an animal is actually infected, or has simply been exposed to the vaccine.

“Unless one can differentiate between vaccinated and infected animals, those animals vaccinated outside the US with the traditional vaccine would be prohibited from entering any country that is designated FMD free.”

However, the new molecular vaccine produced against one strain of FMD at Plum Island does not use a live FMD virus for vaccine manufacture, and can be used to differentiate an infected from inoculated animal using common diagnostic tests.

"This is the biggest news in FMD research in the last 50 years," PIADC Director Dr Larry Barrett was quoted as saying.

"It's the first licensed FMD vaccine that can be manufactured on the US mainland, and it supports a vaccinate-to-live strategy in FMD outbreak response."

The new FMD vaccine took seven years to develop and license.

The article explains that the FMD viral structure includes genetic material surrounded by a coat of proteins called a capsid. The new vaccine produces only the virus coat particles, which form empty viral capsids, and not the entire genome of the virus; thus it lacks the infectious viral nucleic acids.

When the vaccine is injected into the animal the resulting empty viral capsids trigger a protective immune response.

"The absence of the nucleic acids of the real virus allows us to differentiate between vaccinated and infected animals," said Grubman.

"This is critical when determining that an animal is free of infection after an FMD outbreak.

“Now it will no longer be necessary to destroy all the animals in a herd when just a few become infected."

The vaccine has been granted conditional license for use in cattle by the USDA Animal and Plant Health Inspection Service's Center for Veterinary Biologics.

Under the conditional license, the product may be distributed should the need for it arise, as authorised by federal emergency management officials within USDA.

A spokesman said research was now continuing to develop similar vaccines for other strains of FMD.  “DHS has several vaccines for other FMD serotypes ready to enter the licensure process," she said.


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