Studies on the Cytotoxic Effect of Newcastle Disease Virus (NDV) on Ehrlich Ascites Tumor Cells

Abstract

Summary: It has been confirmed that the reaction of NDV with Ehrlich ascites tumor cells resulted in ultimate death of infected cells. This interaction was not accompanied by demonstrable multiplication of infectious, hemagglutinating, or complement fixing particles. Prior to death, cells grew at an accelerated rate for a minimum of 4 hr. The initial growth rate depended on the number of infecting particles, i. e., a very large number of viral particles per tumor cell produced no increase in growth rate, whereas an increased degree of stimulation was caused by smaller numbers of particles per cell. Hyperplasia was followed by disappearance of cells from the peritoneal cavity in a manner suggesting lysis. The cytotoxic effect was shown to result from the action of the viral particle—the activity followed the virus during adsorption and elution from red blood cells, and during ultracentrifugation. Prior treatment of cells with RDE or with specific anti-NDV immune serum protected against viral damage. Immune serum injected only 15 min after viral inoculation did not prevent death of tumor cells. Cell injury could be prevented by prior treatment of cells with ultraviolet inactivated NDV without concomitant reduction in the power of such cells to combine with infectious NDV. The injurious activity of NDV was readily destroyed by ultraviolet light. However, the cytotoxic property of the virus was not as sensitive to ultraviolet irradiation as was the infectious property of the agent.