ABSTRACT

This chapter discusses the similarities between plant comoviruses and animal picornaviruses and, more specifically, the analogy in genome structure, expression, and replication mechanism between Cowpea mosaic virus (CPMV) and poliovirus. These similarities have considerably influenced ideas about the possible involvement of viral proteins in the replication of CPMV RNA. Among various groups of plant RNA viruses with a positive strand RNA genome are viruses with a mono-, a bi-, and a tripartite genome. The different plant RNA virus groups are further characterized by the structures found at the 5' and 3' termini of their genomic RNAs. The comoviruses are a group of 14 different plant viruses that have the same structural organization of genomic RNAs and virus particles, and use the same mechanism for expression and replication of the viral RNAs. The major difference between comoviruses and picornaviruses is that in comoviruses the genome is divided in two RNA molecules whereas that in picornaviruses is a single RNA molecule.