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 b y aphids. Virus particles have different shape and size, ranging from quasi spherical to bacilliform with length of 37, 43, 48, and 55 nm, r espectively, and a diameter of ca. 18 nm. Virions do not contain lipid s or carbohydrates and possess a single coat protein species with mole cular mass of ca. 24 kDa, which is not required for infectivity. Indiv idual particles contain a single molecule of linear, positive sense ss RNA, constituting ca. 19% of their weight. The genome consists of thre e functional non polyadenylated, capped, positive sense, single-strand ed RNA molecules occurring as three functional species of 3126 nt (RNA 1, monocistronic), 2734 nt (RNA2, monocistronic), and 2438 nt (RNA3, b icistronic). Virions encapsidate a fourth RNA species 2078 nt in size (RNA4) with no apparent messenger activity. Virus replication is thoug ht to occur in the cytoplasm possibly in connection with vesicular str uctures. The strategy of replication encompasses proteolytic processin g and subgenomic RNA production. Oleavirus does not have a complete st raightforward relationship with any of the current genera in the Bromo viridae, but shows homologies in diverging directions with one genus o f the family or another.