IS RUBELLA AN ARBOVIRUS .2. ULTRASTRUCTURAL MORPHOLOGY AND DEVELOPMENT

The morphology of rubella virus and its development in BHK21 and RK13 cells has been studied by electron microscopy. In thin sections, rubella virus has an electron-dense core 30 mμ in diameter, and a total diameter of about 60 mμ. The virus develops by budding through the cytoplasmic membrane or sometimes into cytoplasmic vacuoles. By negative staining, small spikes projecting 5-6 mμ from the viral envelope can be seen. The negatively stained particle tends to be somewhat deformed by drying, but after fixation in isotonic osmium fixative the particle appears spherical and 60-70 mμ in diameter. Both in morphology and development rubella closely resembles certain arboviruses, although there are size differences. It has here been compared directly with Semliki Forest virus and Bunyamwera virus, and the classification of all these viruses is discussed. © 1969.