Structures of Picorna-Like Plant Viruses: Implications and Applications

Abstract

Picorna-like plant viruses that include Como and Nepo genera of the Comoviridae, share similarities in structure, genome organization, and replication strategy with mammalian picornaviruses. Structural studies of comoviruses and a nepovirus contribute to the understanding of icosahedral virus structures, the development of novel methods for investigating macromolecular assemblies, and the infrastructure for virus-based bio- and nanotechnology. It is found that bean pod mottle virus (BPMV) shares similar overall genome organization, replication strategy, and capsid structure with the type member cowpea mosaic virus (CPMV). Structural studies of BPMV provided the first observation of a portion of a viral genome in association with its capsid, and the structural comparison of a nucleoprotein particle with an empty capsid that demonstrated ordering of elements of the capsid. Red clover mottle virus (RCMV) is another member of the comovirus family that was investigated biochemically and genetically and its structure was determined for comparative studies. There are significant structural differences between comoviruses and some nepoviruses in that the capsids of comoviruses are composed of two polypeptides whereas those of nepoviruses are composed of a single polypeptide. The structure of a nepovirus, tobacco ringspot virus (TRSV), was determined. Structural comparison showed that TRSV was likely to be an evolutionary intermediate of development of comoviruses.