Foot-and-mouth disease virus and its molecular structure

Foot-and-mouth disease virus (FMDV) is an important animal pathogen that belongs to the Aphthovirus genus of the Picornaviridae family and infects cattle and other cloven-hoofed animals. Seven serotypes (A, O, C, Asia1, SAT1, SAT2 and SAT3) have been identified serologically, and multiple subtypes occur within each serotype. FMDV enters cells by receptor-mediated endocytosis. By electron microscopy the FMD virion appears to be a round particle with a smooth surface and a diameter of about 25 nm. The FMD viral particle contains a positive-strand RNA genome of about 8500 nucleotides, enclosed within a protein capsid. The virus capsid is made up from 60 copies each of four virus-encoded proteins VP1 to VP4. The FMDV genome is composed of the 5' non-translated region (5'NTR), the coding region, and the 3' non-translated region (3'NTR). The genome encodes a single polyprotein, from which the different viral polypeptides are derived by viral proteases. FMDV populations are genetically and anti-genetically heterogeneous. FMDV have very high mutation rates.