Isolation and characterisation of a new Venezuelan strain of cassava common mosaic virus

A new strain of cassava common mosaic virus, designated C_sCMV-ve, was isolated from cassava (Manihot esculenta Crantz) plants growing in Venezuela. The 520 nm long semi-flexuous virus particles sedimented in sucrose gradients as one component and contained a single coat protein molecule of c. 28 kDa, and a ssRNA of c. 2.1 times 10⁶. A single dsRNA species of c. 4.2 times 10⁶kDA was isolated from virus-infected cassava leaves. In double antibody sandwich enzyme-linked immunosorbent assay, C_sCMV-ve reacted strongly with antisera to C_sCMV and potato virus X, but not with those to other typical members of the potexvirus group. Ultrastructural studies of C_sCMV-ve infected cells showed the presence of large bundles of inclusion bodies in the cytoplasm, a proliferation of the rough endoplasmic reticulum, and large crystals in the peroxisomes. C_sCMV-ve in crude buffered sap or in purified preparations was not mechanically transmitted to known hosts of the Chaya and Brazilian strains of C_sCMV. Isolated virus RNA also failed to infect a range of test-plant species. This is the first report of the presence of C_sCMV in Venezuela.