The cultures including the peptide were incubated for 72 h at 37°C and 5% CO2. The cell supernatants
were collected and stored at -80°C for viral load determination using viral RNA and were quantified using one step qReal time-PCR. Virus quantification by plaque formation assay To determine the virus yield after treatment with different concentrations of peptide, the MLN8237 manufacturer culture supernatants were collected and serially diluted to reduce the effects of the drug residues. A 10-fold serial dilution of medium supernatant was added to new Vero cells grown in 24-well plates (1.5 × 105 cells) and incubated for 1 hr at 37°C. The cells were then overlaid with DMEM medium containing 1.1% methylcellulose. The viral plaques were stained with crystal violet dye after a five-day incubation. The virus titres were calculated according to the following formula: Western OICR-9429 manufacturer blot Cells lysates were prepared for immunoblotting against dengue viral antigen using ice-cold lysis buffer. The amount of protein in the cell lysates was quantified to ensure equal loading (20 μg) of the western blot gels using the 2-D Quant Kit (GE Healthcare Bio-Sciences, USA) according to the manufacturer’s instructions. see more The separated proteins were transferred onto nitrocellulose membranes and then blocked with blocking buffer. The membrane was incubated overnight with anti-DENV2
antibody specific to the viral NS1 protein (Abcam, UK, Cat. no. ab41616) and an anti-beta actin antibody (Abcam, UK, Cat. no. ab8226). After washing three times, the membranes were incubated with anti-mouse IgG conjugated to horseradish peroxidase (Dako, Denmark) at 1:1,000 for two h. Horseradish peroxidase substrate was added to for colour development. Indirect immunostaining To examine the efficacy of the Ltc 1 peptide for reducing viral particles, HepG2
cells were grown on cover slips in 6-well plates and infected with DENV2 at an MOI of 2. The DENV2-infected cells were then treated with 25 μM peptide for 24 h. The cells were washed three times with PBS to remove the peptide residues and then fixed with ice-cold Montelukast Sodium methanol for 15 min at -20°C. After washing, the cells were incubated with coating buffer for 1 h at room temperature. A mouse antibody specific to the dengue envelop glycoprotein (Abcam, UK, Cat. no. ab41349) was added, and the cells were incubated overnight at 4°C. The cells were washed three times with PBS and incubated for 30 min with an anti-mouse IgG labelled with FITC fluorescent dye (Invitrogen, USA, Cat. no. 62-6511). To stain the cell nuclei, Hoechst dye was added (Invitrogen, USA, Cat. no. H1399) for the last 15 min of the incubation. Viral RNA quantification The DENV2 copy number was quantified in the culture supernatants using one-step quantitative real-time PCR. Known copies of the viral RNA were 10-fold serially diluted to generate a standard curve.