An Electron Microscope Study of Tomato Spotted Wilt Virus in Sections of Infected Cells and in Negative Stain Preparations

Abstract

Mature particles and the early stages of growth of tomato spotted wilt virus (TSWV) were examined by electron microscopy in thin sections and by negative staining. Early evidence of infection included: (a) amorphous, darkly stained material in the cytoplasm; (b) spherical virus-like particles 100 nm. in diameter, with two concentric membranes; (c) configurations interpreted as membranes budding to form the particles in (b); (d) mature virus particles resembling the inner membranes plus cores of the particles in (b). Similar structures were seen in thin sections of developing local lesions. Local and systemic infections more than five days old contained only mature particles, and not structures (a), (b) and (c).