The U.S. Department of Agriculture (USDA) has designed a molecular vaccine to protect against one strain of foot-and-mouth disease (FMD), which does not use the live FMD virus.

The vaccine, created at the Department of Homeland Security Science and Technology Directorate’s (S&T) high-containment Plum Island Animal Disease Center (PIADC), can be used to differentiate infected and inoculated animals by using common diagnostic tests.

The news is the biggest in FMD research in the last 50 years, according to PIADC director Larry Barrett. “It’s the first licensed FMD vaccine that can be manufactured on the U.S. mainland, and it supports the vaccinate-to-live strategy in FMD outbreak response.”

As the United States is an FMD-free zone, and has been since 1929, no vaccines created by using the FMD virus can be administered or produced in the country, which also means that animals vaccinated outside the United States with a traditional inoculation would also be prevented from entering the country.

Originally discovered by PIADC’s Marvin Grubman, the vaccine has been in development and licensing for seven years and provides a defense against a possible outbreak of FMD in the United States, which would cost an estimated $5 billion. The vaccine produces FMD virus coat particles (a shell) only, which forms a protein called a capsid. As such, the vaccine is missing part of the virus’ genome and so has no infectious viral nucleic acids, which means the virus is not present. The empty viral capsids, however, are enough to trigger a protective immune response when injected into the animal.

“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,” Grubman says.

Branch chief at the PIADC John Neilan developed a way to address the immune response to the vaccine, which made it possible to achieve the level of effectiveness required for a USDA license. The vaccine was recently given a conditional licence for use in cattle by USDA’s Animal and Plant Health Inspection Service’s Center for Veterinary Biologics and can also be distributed if an outbreak arises.

S&T’s Agricultural Defense Branch chief Michelle Colby says: “Our work isn’t over yet, This vaccine protects against just one strain of FMD, so this is just the tip of a growing iceberg.”