Chloroquine: Protection Against Virus-induced Cell Damage Without Inhibition of Virus Growth

Abstract

The RNA in chick embryo fibroblasts is degraded after infection of the cells by Newcastle disease virus (NDV) (Huo & Wilson, 1969). The nucleases which cause this degradation may have been located in lysosomes which break down following virus infection, as is the case in poliovirus infected KB cells (Flanagan, 1966). This latter observation suggested that the NDV induced degradation of cell RNA might be prevented by treating virus infected cells with an agent which stabilizes lysosomes. This hypothesis was examined using chloroquine diphosphate which has been reported to stabilize lysosomes in some cell types (Weissman, 1964) and to cause lysosomal breakdown in other cell types (Fedorko, Hirsch & Cohn, 1968). It was found that chloroquine did in fact protect the RNA of NDV infected cells, but not because it stabilized the lysosomes in these cells. The RNA of chick embryo fibroblasts was labelled by exposing cell cultures to Eagle's medium (8% calf serum) containing 1 µc/ml. of 5-[3H]-uridine for 16 hr.