Herpesvirus-induced cell fusion that is dependent on cell surface heparan sulfate or soluble heparin

The entry of enveloped viruses into animal cells and the cell-to-cell spread of infection via cell fusion require the membrane-fusing activity of viral glycoproteins. This activity can be dependent on variable cell factors or triggered by environmental factors. Here we show that cell fusion induced by herpes simplex virus glycoproteins is dependent on the presence of cell surface glycosaminoglycans, principally heparan sulfate, or on the addition of heparin to the medium. The role of the glycosaminoglycan is probably to alter the conformation of a viral heparin-binding glycoprotein required for the fusion.