ASSOCIATION OF VIRIONS AND COAT PROTEIN OF TOBACCO VEIN MOTTLING POTYVIRUS WITH CYLINDRICAL INCLUSIONS IN TOBACCO CELLS

The course of infection with tobacco vein mottling potyvirus (TVMV) in tobacco protoplasts and leaves was studied by electron microscopy wit h immunogold labeling. In sections of protoplasts inoculated with TVMV RNA 10, 21, or 45 h prior to fixation, antibodies to TVMV coat protei n (CP) were bound to cylindrical inclusions and individual virions usu ally associated with these inclusions. Also, in sections of leaves fro m plants inoculated with TVMV 5, 14, or 21 days prior to fixation, ant ibodies to TVMV CP were bound to cylindrical inclusions and aggregates of virions in the cytoplasm. In protoplasts and leaves, the specific labeling of CP on the cylindrical inclusions increased significantly w ith time postinoculation, and in most cases, these inclusions were ass ociated with the rough endoplasmic reticulum. Association of TVMV viri ons and CP with cylindrical inclusions at early stages of infection su ggests that these inclusions may be involved in potyviral protein synt hesis and virion assembly in addition to their possible role in viral RNA replication.