The foot-and-mouth disease virus (FMDV) is the pathogen that causes foot-and-mouth disease. It is a picornavirus, the prototypical member of the Aphthovirus genus. The disease, which causes vesicles (blisters) in the mouth and feet of bovids, suids, ovids, caprids and other cloven-hoofed animals is highly infectious and a major plague of animal farming. The virus particle (25-30 nm) has an icosahedral capsid made of protein, without envelope, containing a single strand of ribonucleic acid (RNA) containing a positive encoding of its genome. When the virus comes in contact with the membrane of a host cell, it binds to a receptor site and triggers a folding-in of the membrane. Once the virus is inside the host cell, the capsid dissolves, and the RNA gets replicated, and translated into viral proteins by the cell's ribosomes using a cap-independent mechanism driven by the internal ribosome entry site element. The foot-and-mouth disease virus occurs in seven major serotypes: O, A, C, SAT-1, SAT-2, SAT-3, and Asia-1. These serotypes show some regionality, and the O serotype is most common.