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Traditional vaccines for FMD typically have three 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 U.S. with the traditional vaccine would be prohibited from entering any country that is designated FMD free. The United States has been FMD-free since 1929, but that is no guarantee that the disease will not strike again, as the UK learned in 2001 after being FMD-free for 34 years.
Now, at the Department of Homeland Security Science and Technology Directorate's high-containment Plum Island Animal Disease Center (PIADC), located off the tip of Long Island, scientists have produced a molecular vaccine against one strain of FMD, that 1) does not use a live FMD virus for vaccine manufacture, and; 2) 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," says PIADC Director Dr. Larry Barrett.
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."
Wednesday July 3, 2012/ Science Daily.
http://www.sciencedaily.com
