Nerve cell fusion in a case of subacute sclerosing panencephalitis.

Evidence indicating cell membrane fusion among cells and their processes where subacute sclerosing panencephalitis (SSPE) virus is present is shown in an ultrastructural study of a brain biopsy. Virus budding from plasma membrane was not seen. These rare findings reinforce the hypothesis of cell-to-cell transmission as the most likely mechanism of SSPE virus infection. The presence of fused membranes between cell processes and cell soma probably explains the rapid spread of this virus throughout the nervous system.