Membrane fusion as a mechanism of simian virus 40 entry into different cellular compartments

Abstract

Permissive and nonpermissive SV-40-infected [African green monkey kidney CV-1] cells were ultrastructurally analyzed. Viral particles were found in the cytoplasm, rough endoplasmic reticulum, nuclear envelope, lysosomes and mitochondria. On entering the cell the virion obtains a tight membrane envelope. It seems to be released from the envelope upon fusion with other membranes of the cell or aggregated into tubular membrane specializations upon fusion with other membrane-enveloped particles. Reconstructed morphological sequences and the finding of SV-40 in different spaces of the cell suggest that entry of SV-40 into the different compartments and eventually into the site of replication is facilitated by its capacity for being enveloped by a variety of membranes (notably the cell membrane and the nuclear membrane) and the sequential fusion and fission of these membranes.