Mouse Elberfeld (ME) virus determines the cell surface alterations when mixedly infecting poliovirus-infected cells.

The surface alterations of HEp-2 cells induced by mixed infection with two different picornaviruses (poliovirus and ME virus) were compared by scanning electron microscopic and transmission electron microscopic studies and by 51Cr-release assay. The contribution of each of the viruses to the resulting surface changes was discernible, as investigations on the chronology of the cytopathic alterations demonstrated that the changes were distinct for either virus. The surface of ME virus-infected cells was characterized by large membranous structures ('sheets' and blebs) representing huge vacuoles. These sheets were not seen in poliovirus-infected cells. Poliovirus induced more prominent cell pycnosis, elongation of filopodia and condensation of collapsed microvilli on the cell surface than ME virus. Mixed infection with these two viruses led to surface alterations typical for ME virus. These ME virus-specific changes occurred irrespective of poliovirus reproduction or its inhibition by guanidine. ME virus-specific alterations also predominated in cytolytic membrane damage as expressed by 51Cr-release from infected cells. 51Cr-release was more pronounced from ME virus than from poliovirus-infected cells, even when ME virus reproduction was suppressed by interfering poliovirus. However, alteration of the internal structures of the infected cells was only dominated by ME virus when the reproduction of poliovirus was suppressed.