10.1128/JVI.07089-11 [PMC free of charge content] [PubMed] [CrossRef] [Google Scholar] 37. the NS3-5B-coding area can be expanded at 30C, using the second option strain being utilized for all those constructs including duplicated sequences. RNA electroporation and transcription of cells. Five micrograms of plasmid DNA was linearized with XbaI MKI67 (Fermentas), refined with mung bean nuclease (NEB), purified by phenol-chloroform removal, ethanol precipitated, and treated with the RNAsecure reagent (Ambion) according to the manufacturer’s recommendations. The DNA was used in a 50-l reaction mixture comprising 40 devices T7 polymerase plus connected buffer Epristeride Epristeride (Fermentas), 50 devices RiboLock RNase inhibitor (Fermentas), and 8 mM recombinant nucleoside triphosphates (Promega). After incubation at 30C for 6 h, 2.5 units RQ1 DNase was added and the reaction mixture was remaining at 37C for a further 30 min. RNAs were recovered using RNA Clean & Concentrator-25 spin columns (Zymo Study), and transcript integrity was assessed by gel electrophoresis. Huh7 or Huh7.5 cells were detached by trypsin, washed twice in ice-cold diethyl pyrocarbonate (DEPC)-treated phosphate-buffered saline (PBS), and resuspended at a final density of 1 1 107 cells/ml in DEPC-treated PBS. Four hundred microliters of cells was typically mixed with 2 g of RNA transcript, transferred to a 0.4-cm-gap electroporation cuvette (VWR), and pulsed using a Bio-Rad Gene Pulser apparatus arranged at 270 V and 960 F. However, 0.7 pmol RNAs (equivalent to 2 g of SGR-wt) were used in the experiments whose results are explained in Fig. 5 to compensate for variations in transcript size. Open in a separate windowpane FIG 5 Intragenomic complementation of defective HCV RNA replication. (a) Schematic representation of bicistronic replicon constructs with the 1st cistron encoding a luciferase-FMDV2A reporter fusion protein linked to NS4B (Rep_R2NS4B/3-5BFLAG), NS5A (Rep_R2NS5AV5/3-5BFLAG), and NS3-NS5A (Rep_R2NS3-5AV5/3-5BFLAG). (b) Transient replication assays in Huh7.5 cells. wt, S2208I, and G1911A refer to the NS3-5B polyprotein Epristeride indicated in the second cistron for each construct; wt denotes wt versions of NS5A and NS4B, S2208I shows the mutation in NS5A, and G1911A denotes the mutation in NS4B. The GDD create expresses a nontagged version of NS5A in the 1st cistron and NS3-5B comprising a defective HCV RNA polymerase in the second cistron. Luciferase activity was monitored over 72 h and normalized to that in the 4-h time point (mean SD; = 2). Transient replication assays. To assess viral RNA replication, Huh7.5 cells were electroporated with RNA transcripts and then sampled over a 72-h time period using either a luciferase assay system (Promega), a luciferase assay kit (Biotium), or a dual-luciferase reporter assay system (Promega). In the case of for 6 min, and transferred onto naive subconfluent Huh7.5 cells, which were then remaining for a further 48 h before assaying luciferase activity. Western blot analysis. Epristeride Except when phosphatase treatment was required, cells were lysed in radioimmunoprecipitation assay buffer (0.1% sodium dodecyl sulfate [SDS], 0.5% sodium deoxycholate, 1% NP-40, 150 mM NaCl, 50 mM Tris [pH 8.0]) supplemented with 2 Complete protease inhibitor (Roche), 10 mM NaF, and 1 mM Na3VO4. When phosphatase treatment was required, cells were washed in Tris-buffered saline (TBS; 150 mM NaCl, 50 mM Tris [pH 7.5]) and lysed in TBS supplemented with 1% Triton X-100, and the clarified lysate was supplemented with 0.16 units/l calf intestinal phosphatase (Fermentas) and incubated at 37C for 60 min. All lysates were separated by SDS-PAGE and transferred to a polyvinylidene difluoride membrane (Millipore). Membranes were Epristeride clogged with 5% (wt/vol) low-fat dried milk, 0.1% Tween 20 (Merck) in Tris-buffered saline. Antibodies used included sheep polyclonal anti-NS3 and anti-NS5A (a gift from M. Harris), goat polyclonal anti-GFP (Serotec), rabbit polyclonal anti-NS4B, mouse monoclonal anti-NS3 (BioFront) and anti-V5 (a gift from R. Randall, University or college of St. Andrews), and rat monoclonal anti-FLAG (Biolegend). Indirect immunofluorescence. Huh7.5 cells transduced with a relevant baculovirus constructs(s) at 5 107 PFU/ml for 4 h were allowed to recover for a further 4 h before electroporation with RNA transcripts and seeding onto glass coverslips. Cells were fixed at 24 h postelectroporation with 4% paraformaldehyde, washed in PBS, permeabilized in saponin buffer (0.1% saponin, 10% FCS, 0.1% sodium azide) for 1 h at 4C, labeled with rat anti-FLAG primary.
