Additional details are provided in the Supporting Information. HEK293T, Chinese hamster ovary, Buffalo rat liver, Huh7, Huh7.5-GFP, and Huh7.5.1 cells were cultured as described.18, 23-25 Primary human hepatocytes were isolated as described.18 Chinese hamster ovary and Buffalo rat liver cells expressing SR-BI were produced as described.11, 15, 23 Polyclonal15 and monoclonal antibodies (mAbs) directed against the extracellular loop of SR-BI were raised by genetic immunization of Wistar rats and

Balb/c mice as described15 according to proprietary technology (Aldevron GmbH, Freiburg, Germany). Anti–SR-BI mAbs were purified using protein G affinity columns and selected via flow cytometry for their ability to bind to human SR-BI.15 To determine the affinity of the anti–SR-BI mAbs for human SR-BI, Huh7.5.1 cells were incubated

with increasing concentrations of mAbs, and binding was assessed using Selleck Dasatinib flow Doxorubicin cost cytometry. Kd values were determined as half-saturating concentrations of the mAbs.26, 27 Antibodies will be provided on request using a material transfer agreement (MTA). Anti-CD81 (JS-81), anti–SR-BI (CLA-1), and phycoerythrin-conjugated anti-mouse antibodies were from BD Biosciences. Anti-His and fluorescein isothiocyanate–conjugated anti-His antibodies were obtained from Qiagen, rabbit anti-actin (AA20-30) antibodies were obtained from Sigma-Aldrich, and mouse anti-NS5A antibodies were obtained from Virostat. Anti-E1 (IGH520, IGH526, Innogenetics), anti-E2 (IGH461, Innogenetics; AP33, Genentech; CBH23, a kind gift from S.K.H. Foung), and patient-derived

anti-HCV immunoglobulin G (IgG) have been described.16, next 25, 27 Luciferase reporter cell culture-derived HCV (HCVcc), HCV pseudoparticles (HCVpp), murine leukemia virus pseudoparticles, and vesicular stomatitis virus glycoprotein pseudoparticles (VSV-Gpp), infection and kinetic experiments have been described.15, 18, 25, 27, 28 Unless otherwise stated, HCVcc experiments were performed using Luc-Jc1, and infection was analyzed in cell lysates via quantification of luciferase activity.29 For combination experiments, each antibody was tested individually or in combination with a second antibody. Huh7.5.1 cells were preincubated with anti–SR-BI or control mAb for 1 hour and then incubated for 4 hours at 37°C with HCVcc (Luc-Jc1) or HCVpp (P02VJ) (preincubated for 1 hour with or without anti-envelope antibodies). Synergy was assessed using the combination index and the method of Prichard and Shipman.30-32 Cell viability was assessed using a MTT test.2 Recombinant His-tagged soluble E2 (sE2) was produced as described.23 Huh7.5.1 cells were preincubated with control or anti–SR-BI serum (1:50), anti–SR-BI or control mAbs (20 μg/mL) for 1 hour at room temperature, and then incubated with sE2 for 1 hour at room temperature. Binding of sE2 was revealed using flow cytometry as described.18, 23 Huh7.5.