Structure of inclusion bodies of cabbage black ring virus.

Inclusions in cells of Nicotiana glutinosa infected with a horse-radish strain of cabbage black ring virus (CBRV) were investigated on ultrathin sections. Large amorphous inclusions contained cellular constitutents showing usually no pathological alterations. Lamellar inclusions (bundles, circular inclusions, pinwheels), closely associated with endoplasmic reticulum, occurred frequently in areas of cytoplasm showing no vesiculation. Sac-like structures composed of concentric lamellae were observed in the cytoplasm or intruding into the vacuole. Spherosomes containing each a single crystal were found very often in the cytoplasm. Masses of virus particles in a parallel arrangement were usually located at the tonoplast.