UPTAKE OF POLIOVIRUS INTO THE ENDOSOMAL SYSTEM OF HELA-CELLS

To understand the topology and mechanism of poliovirus uncoating, the question of whether intact virions can be endocytosed by the host cell was studied by a combination of various techniques. In order to preve nt alteration of the virus to subviral particles, Hela cells were infe cted at 26 degrees C. At this temperature the majority of cell-associa ted virions remained at the plasma membrane, whereas a smaller amount accumulated in vesicles having the same mobility (upon free-flow elect rophoresis) and migration behaviour on Nycodenz density gradients as e arly and late endosomes. Co-localization of native poliovirions with e ndosomal markers was verified by peroxidase-induced diaminobenzidine d ensity-shift of endosomal vesicles. Internalization of poliovirions in to endosomes makes it likely, but does not prove that viral RNA can be released into the cytoplasm from the vesicular compartment.