The titer of the stock was 5 × 106 focus-forming units/mL. The luciferase-based

HCV pseudotyped retroviral particle (HCVpp) infection assay was used as previously described. 23 HSV type 1 strain HF (HSV-1; ATCC VR-260) was used to infect Vero cells, then seeded in 96-well plates for 1 hour at 37°C. Five days after infection, titers were calculated by quantifying the cytopathic effect. BVDV strain NADL and YFV strain 17D were used to infect MDBK or Huh-7 cells at a multiplicity of infection (MOI) of 1.5 or 1, respectively, seeded on coverslips for 1 hour at 37°C, and cultured for either 15 or 23 hours. MOIs were determined based on BVDV and YFV infectious titers, determined on MDBK and Huh-7 cells, respectively, and on the number of cells at the inoculation step. Stocks of Toto1101/Luc, 24 a Sindbis virus (SINV) expressing the Firefly

luciferase (kindly provided by M. MacDonald, Rockefeller University, New York, Cisplatin in vitro NY), were generated as previously described. 24 The inoculation period was 1 hour, and cells were lysed at 23 hours postinfection. Huh-7 cells were inoculated for 2 hours with HCVcc in 35-mm wells of six-well cell-culture plates or were electroporated with JFH1-ΔE1/E2 RNA. HCV core antigen, expressed within cells or secreted into the supernatant, was quantified using chemiluminescent microparticle technology (Architect HCV CHIR-99021 research buy Ag Test; Abbott SA, Rungis, France), as previously described. 25 In parallel, total amounts of proteins in cell lysates were quantified using the bicinchoninic acid assay (Sigma-Aldrich). Infected cells grown onto glass coverslips were processed for IF detection of viral proteins, as previously described. 26 Nuclei were stained with 1 μg/mL of DAPI. Coverslips were observed with a Zeiss Axiophot microscope equipped with either 10× or 20× magnification objectives (Carl Zeiss AG, Oberkochen, Germany). Fluorescent signals were collected medchemexpress with a Coolsnap ES camera (Photometrix, Kew, Australia). For quantification, images of randomly picked areas from each coverslip were recorded. Subconfluent cell cultures

grown in 96-well plates were incubated in culture medium. An MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium]-based viability assay (CellTiter 96 aqueous nonradioactive cell proliferation assay from Promega) was conducted as recommended by the manufacturer. Huh-7 cells seeded on coverslips in 24-well plates were infected with HCVcc for 2 hours. The inoculum was removed and replaced with culture medium containing 1% Seaplaque low-melting-temperature agarose (Lonza, Walkersville, MD) or 3/11 anti-E2 neutralizing mAb at 50 μg/mL. At 3 days postinfection, the foci were detected using indirect IF. Huh-7 cells were infected with JFH1-Luc in 24-well plates for 1 hour at 4°C (attachment/binding period), washed with serum-free medium, and incubated for another 1 hour at 4°C (postattachment/-binding period).