For fluorescence microscopy on fixed cells, HeLa-prME cells were grown on glass coverslips. Cells were fixed, permeabilized, and incubated with anti-DV human sera (1:200) and anti-Erp72 Rabbit polyclonal Ab (1:200, Stressgen Bioreagents, Ann Arbor, MI, USA), anti-ERGIC-53 mAb (1:1000, Alexis Biochemicals, Farmingdale, NY, USA), or anti-Golgin-97 mAb (1:50, Invitrogen, Carlsbad, CA, USA), followed by the incubation with corresponding secondary antibody conjugated with FITC or TRITC. Nuclei were stained with DAPI and coverslips were mounted on glass slides for analysis. Fixed cells were visualized under AxioObserver Z1 inverted motorized fluorescent microscope using the ApoTome module and piloted through the Axiovision 4.6 software and images were acquired through the MRm AxioCam high resolution CCD camera (Carl Zeiss, Germany).