TRANSPORT OF VIRAL GLYCOPROTEINS AND ITS MODULATION BY MONENSIN

Distinct pathways of membrane glycoprotein transport exist in polarized epithelial cell monolayers, differing in their sensitivity to monensin, a sodium ionophore. Monensin blocks the transport of secretory and membrane glycoproteins at the level of the Golgi complex, which appears dilated as an effect of the drug. Influenza hemagglutinin (HA) protein continues to be transported to the surface of monensin-treated cells, is cleaved into HA(1) and HA(2) and is incorporated into budding influenza virus particles. On the other hand, vesicular stomatitis virus (VSV) glycoprotein appears to accumulate in the membranes of the dilated Golgi apparatus of monensin-treated cells. This chapter discusses the effects of monensin on the kinetics of transport of viral membrane glycoproteins to the cell surface. It also discusses the effect of the ionophore on the directional transport of viral glycoproteins in Madin-Darby canine kidney cells doubly-infected with influenza virus and VSV and on the replication of viruses that are assembled at intracellular membranes.