Oleavirus, a new genus in the family Bromoviridae

Oleavirus is a monotypic genus having olive latent virus 2 (OLV-2) as the type species. OLV-2 is transmitted by inoculation of sap but not by aphids. Virus particles have different shape and size, ranging from quasi spherical to bacilliform with length of 37, 43, 48, and 55 nm, respectively, and a diameter of ca. 18 nm. Virions do not contain lipids or carbohydrates and possess a single coat protein species with molecular mass of ca. 24 kDa, which is not required for infectivity. Individual particles contain a single molecule of linear, positive sense ssRNA, constituting ca. 19% of their weight. The genome consists of three functional non polyadenylated, capped, positive sense, single-stranded RNA molecules occurring as three functional species of 3126 nt (RNA1, monocistronic), 2734 nt (RNA2, monocistronic), and 2438 nt (RNA3, bicistronic). Virions encapsidate a fourth RNA species 2078 nt in size (RNA4) with no apparent messenger activity. Virus replication is thought to occur in the cytoplasm possibly in connection with vesicular structures. The strategy of replication encompasses proteolytic processing and subgenomic RNA production. Oleavirus does not have a complete straightforward relationship with any of the current genera in the Bromoviridae, but shows homologies in diverging directions with one genus of the family or another.