TJP1 and viral infectious disease: Moreover, treatment with nafamostat at 1 μM also prevented the epithelial barrier disruption (removal of epithelial ZO-1-containing tight junctions) that occurs following virus infection, and this protective effect of inhibiting host proteases was similar to that induced by treatment with the direct-acting antiviral drug oseltamivir, as indicated by immunofluorescence microscopy (Figure 3C).