Immunoelectron microscopy on the topographical distribution of the poliovirus receptor

The topographical distribution of the poliovirus receptor on the cell surface was demonstrated by immunoelectron microscopy using monoclonal antibodies and immunogold markers. The receptor appeared in small clusters, which were randomly distributed over the cell surface and along cellular processes. The distribution pattern of the clusters corresponded to that of absorbed and immunogold-labelled poliovirus particles and suggests a multivalent organization of poliovirus binding sites. Freeze-fracturing and ultrathin sectioning did not reveal any specific ultrastructures within the plasma membrane at labelled receptor areas. Incubation of native cells with anti-receptor antibodies did not remove the receptor molecule from the cell surface nor did it induce ultrastructural alterations within the plasma membrane. The antibody-receptor complexes exhibited lateral mobility within the plasma membrane and were able to aggregate into large immune complexes after incubation with a second ligand.