ABSTRACT

The name Nepovirus, an acronym for nematode transmitted polyhedral virus, was suggested for the group. Nepoviruses have polyhedral particles 28 to 30 nm in diameter, usually of three types which can be separated into top, middle, and bottom sedimenting components. Most Nepoviruses have wide host ranges, and many infect perennial plants and trees. Only a very few Nepoviruses, considered to be sufficiently different to warrant distinct names, have been shown to be distantly related serologically. The Nepovirus genome is a bipartite in that both ribonucleic acid (RNA) 1 and RNA 2 are essential for infectivity. Nepoviruses require both RNA 1 and RNA 2 for normal infection and virus multiplication. Several Nepoviruses have been found to contain satellite RNAs dependent for their replication on the genomes of their helper viruses. Numerous pseudorecombinants have been constructed in vitro from closely related Nepoviruses.