FIG. 2.

Clathrin-dependent endocytosis of FMDV. (A) Sucrose inhibits FMDV infection. SW480-αvβ6 cells were treated with sucrose for 0.5 h prior to infection (MOI of ∼0.3) with FMDV for 1 h in the presence of sucrose. Mock-treated cells were treated with DMEM (see Materials and Methods). Infection was quantified as described for Fig. 1. The number of infected cells in the sucrose-treated samples was expressed as a percentage of the number of infected cells in mock-treated samples. The means and standard deviations from three observations are shown. (B to E). Sucrose inhibits uptake of both FMDV and transferrin. Transferrin and FMDV were detected using the confocal microscope as described in Materials and Methods. SW480-αvβ6 cells were treated with 0.4 M sucrose (C and E) for 0.5 h prior to internalization of Alexa-488-conjugated transferrin (green) or FMDV (red) for 20 min in the presence of sucrose. Mock-treated cells were treated as described above in the absence of sucrose (B and D). Sucrose treatment inhibited uptake of both transferrin and FMDV (C and E). (F and G). Expression of AP180C inhibits infection by FMDV. SW480-αvβ6 cells were transfectedto express c-myc-tagged AP180C and subsequently infected with FMDV (see Materials and Methods). Transfected and/or infected cells were detected using the confocal microscope. Transfected cells (green) were detected using the anti-c-myc antibody, and infected cells (red) were detected with a rabbit polyclonal serum to FMDV (see Materials and Methods). The nuclei were stained with DAPI and are shown as blue. Expression of AP180C inhibited infection, as the transfected cells showed a reduced infection compared with the untransfected cells. Bars, •••.