Physicochemical membrane changes in ehrlich ascites tumor cells infected with oncolytic influenza virus

Summary Physicochemical changes in the cell membrane of Ehrlich ascites tumor (EAT) cells during infectionin vitro with oncolytic influenza A₀ virus, strain WSA, were studied by means of cell electrophoresis.The surface charge of virus-infected cells, when compared to the mean electrophoretic mobility (EPM) of non-infected EAT cells, was reduced in two consecutive steps. The first reduction of EPM occurred in the course of virus adsorption to the cell membrane and was related to the action of viral neuraminidase on the receptor glycoproteins; inactivated and fully active virus had the same effect. In contrast to this, the second decrease of EPM, beginning at 180 minutes after infection, was strictly related to virus replication. By comparison with the effect of bacterial neuraminidase (Vibrio cholerae) on EPM of infected and non-infected EAT cells, the second reduction during virus replication was shown to be due to the removal of negatively charged moieties from the cell surface. This might also have been caused by enzymatic activity (of the replicating virus) or by incorporation of sialic acid-free viral components into the host cell membrane. Neither cationogenic groups, such as could occur in virus-coded proteins, nor unspecific adsorptions from the suspending fluid were found to influence the electrophoretic behaviour of WSA-infected cells.The removal of negatively charged moieties from the cell membrane is discussed in relation to the increased immunogenicity of WSA-infected EAT cells.