ABSTRACT
Cowpea mosaic virus (CPMV), type member of the comovirus group, has now been studied for more than 20 years and is one of the best characterized plant viruses. The comovirus group contains viruses with a bipartite, single-stranded RNA genome separately encapsidated in icosahedral particles. Soon after infection of cowpea cells, cytopathic structures are induced which contain large numbers of membranous vesicles. The genome of CPMV encodes a number of nonstructural polypeptides which may be involved in processes like induction of cytopathic membrane structures, RNA replication, proteolytic cleavage of primary translation products, encapsidation, and transport of RNA. Cowpea severe mosaic virus (CPSMV) is the only other comovirus for which information on its expression in vivo is available. The analogy between comoviruses and picornaviruses is not limited to structural features of the genomic RNAs and their mode of expression but includes the organization of the genes involved in viral RNA replication.
