Cowpea mosaic virus (CPMV) is the type member of the genus Comovirus, which comprises one of three genera of the family Comoviridae. The genome of CPMV consists of two molecules of positive-strand RNA, which are separately encapsidated in isometric particles consisting of 60 copies each of two types of coat protein. Since its initial isolation, CPMV has been extensively studied from both a genetic and structural point of view and has become a paradigm for plant viruses that express their genome through the synthesis and processing of precursor polyproteins. In this regard, as well as in its particle structure, CPMV resembles other members of the family Picornaviridae. More recently, the virus has been used for a number of biotechnological applications.