PATHWAY OF RUBELLA-VIRUS INFECTIOUS ENTRY INTO VERO CELLS

The mechanism and the kinetics of rubella virus (RV) penetration into Vero cells were studied. By using pronase or acid treatment to inactiv ate virus which had adsorbed to cell membrane but had not been interna lized, it was found that a period of 7 h was required in order for all of the adsorbed virus to enter the host cells. Lysosomotropic agents (monensin, methylamine, ammonium chloride and chloroquine) were used t o study the mechanism by which RV penetrates host cells. Virus replica tion was inhibited if treatment of cells with these compounds was perf ormed for at least 9 h after infection. However, if extracellular adso rbed virions were eliminated by acid treatment following removal of th e lysosomotropic compounds, RV replication was completely inhibited by treatment with these drugs for any time period after adsorption. This indicated that the prolonged period of treatment with these compounds necessary to inhibit virus replication is due to the slow rate of RV internalization. None of the compounds had any effect on infection ini tiated by transfection of RV RNA, confirming that these drugs were exe rting their inhibitory activity at penetration. The inhibition of RV r eplication by lysosomotropic compounds indicates that RV penetrates ho st cells by the endosomal pathway.