o.i., multiplicity of infection; MVB, multivesicular bodies;

NHS, normal human serum; PHH, primary human hepatocytes; RT-qPCR, reverse transcription followed by quantitative real-time polymerase chain reaction. HepaRG cells were cultured as described.5, 9 The medium was renewed every 7 days. HCV infection experiments were carried out using well-characterized purified HCVsp (genotype 3a), which contained 106 copies of HCV RNA per mg of protein (Supporting Materials and Methods, Fig. 1). HepaRG cells were inoculated 3 days postplating (p.p.) for 18 hours at 37°C with 105 copies of HCV RNA corresponding to multiplicity of infection Erlotinib (m.o.i.) of 1, either in the absence or in the presence

of normal human serum (NHS) at a final concentration of 1%. For inhibition experiments, the HCVsp inoculum was preincubated for 2 hours at 37°C with the D32.10 mAb at a final concentration of 0.5 μg/mL. On day 1 postinfection (p.i.), extensive washings (3-4 times) of the cells were done. The medium was changed at day 7 p.p. and then each week at days 14, 21, 28 up to day 66. HCV-associated particles were purified from supernatants collected every 7 days and clarified by low-speed

centrifugation, as described.10 Cells were harvested at days 28 and 56 p.p. for detection of E1E2 and core antigens by immunohistochemistry. selleck HCVsp-infected see more HepaRG cells were frozen at day 56 p.p. The density distributions of secreted HCV particles were analyzed on either a sucrose density gradient (10%-60% w/w)10 or an iodixanol (OptiPrep; Axis-Shield, AbCys S.A. France) gradient prepared as described by Nielsen et al.11 HCV particles concentrated (50-100 times) and purified from culture media were subjected to isopycnic centrifugation (200,000g for 48 hours at 4°C) in the SW41 rotor of a Beckman centrifuge. Fractions (0.6 mL or 1.2 mL) were collected from the bottom of the tube and the density of each was determined by refractometry. For HCV RNA analysis, lysis buffer was directly added to the ultracentrifugation pellets. RNA was extracted using QIAamp Viral RNA mini Kit (Qiagen). Reverse transcription was performed using primers located in the 5′ NCR region of all HCV genotypes.12 After a denaturing step, the RNA template was incubated at 60°C for 1 hour with 7.5 U thermoscript reverse transcriptase (kit Gibco/BRL) and then treated with 20 U RNaseOut for 20 minutes at 37°C.