Properties of virus particles, nucleic acid and coat protein of cycas necrotic stunt virus.

Abstract

Cycas necrotic stunt virus (CNSV; considered to belong to nepovirus group) isolated from cycad plants was characterized further. The sedimentation coefficients of the components M (middle) and B (bottom) were 85S and 112S, and buoyant densities in CsCl were 1.404 and 1.472 g/cm3, respectively. When the infectivity of the components was tested, the mixture of both components was five to twenty times more infectious than either particle alone. M and B components contained single-stranded RNA species with molecular weight (MW) of 1.5×106 (RNA2) and 2.5×106 (RNA1), respectively. Both RNA1 and RNA2 were necessary for infection. M and B components contained a single major polypeptide with identical MW of 65 K. These properties of virus particles, nucleic acid and coat protein of CNSV confirmed affinities of CNSV to nepoviruses, particularly to tomato black ring virus (TBRV). However, since no serological relationship between CNSV and TBRV or serologically TBRV-related viruses was detected in our previous work, CNSV would be a new nepovirus having similarities to TBRV in biochemical properties.