A Comparison of Cytopathology Caused by Myxoviruses

Abstract

Summary The inhibition by metabolic analogues of the cytopathic effects of myxoviruses on HeLa and L cells indicates that the processes which lead to viral replication are responsible for cytopathology in these systems. Oxythiamine and desoxypyridoxine protected HeLa and L cells from the cytopathic action of PR8 influenza and mumps viruses. These vitamin analogues also inhibited the cytopathology caused by Newcastle disease virus (NDV) in L cells, but destruction of HeLa cells by NDV was unaffected. In the systems in which protection was demonstrated, there was concomitant decrease in hemagglutinins and infectivity. Although cortisone also protected the cells from the cytopathic action of the myxoviruses, the production of hemagglutinins and infectious units was unaffected, and release of virus from the infected cells was not inhibited. Prior exposure of HeLa and L cells for 2 hr to heat-inactivated viruses protected the cells from the cytopathic action of active homologous or heterologous viruses. It appeared that receptor destruction was partly responsible for this protective action, but other factors were apparently involved, since interference was most pronounced in systems employing homologous inactive and active virus. L cells surviving the original exposure to NDV or PR8 virus were subsequently resistant to the cytopathic action of the homologous or heterologous virus, but surviving HeLa cells were not. The resistance of the L cells appeared to be related to the presence of an interferon-like substance, but this resistance was lost on serial passage.