Foot-and-Mouth Disease Virus (FMDV) is a member of the Picornaviridae family of viruses, which includes viruses that cause a number of high consequence human and animal diseases in addition to Foot-and-Mouth Disease (FMD), such as hand-foot-and-mouth disease, herpangina, polio, and encephalomyocarditis. FMDV infects domestic and wild cloven-hoofed animals, including bovine, caprine, ovine and swine species that are vital to the livestock industry. Depending on host and virus characteristics, FMD exhibits a broad range of clinical presentations resulting in significant morbidity. Generally, FMD produces fever and soreness, excessive salivation, loss of appetite and large vesicles on the feet, nose and tongue 24 to 72 hours post-infection (hpi). In some cases, complete prostration accompanied by the loss of hooves occurs (for review see refs. 1-4). Although mortality rates are typically low and usually associated with young or immunocompromised animals, the economic consequences of an FMD outbreak, such as dramatic decreases in livestock productivity and banning of the export of animals and animal products, are so significant that FMD is one of the most threatening diseases of domestic animals in the world. In many developing regions of Asia, Africa and South America, FMD is enzootic. Global economic activities and transboundary movement of people and animals presents a significant risk of accidental introduction of FMDV into previously FMDV-free countries. Additionally, terrorist groups may intentionally introduce FMDV into a country that is FMD-free and does not vaccinate against the virus (refs.5-8 and http://www.oie.int; http://iah.bbsrc.ac.uk/virus/Picornaviridae/Aphtovirus/fmd.htm ).