Figure 1. Serum-free Huh7.5 cell cultures produced high-titer sf-HCVcc.

Huh7.5 cells were infected with (A) H77(1a), (B) J4(1b), (C) S52(3a) and (D) ED43(4a) JFH1-based Core-NS2 recombinants in DMEM + 10% FBS for 18 hours. Cells were split into two replicate DMEM + 10% FBS cultures. When ~80% of culture cells were infected, as determined by HCV NS5A immunostaining, one replicate culture was maintained in DMEM + 10% FBS (black bars), while the other replicate culture was maintained in AEM (grey bars). At the indicated day post infection, supernatants were collected and DMEM + 10% FBS cultures were split, while fresh medium was added to AEM cultures as described in Materials and Methods. Supernatant HCVcc infectivity titers are shown as means of 3 replicates with standard error of the mean (SEM). The lower limit of detection in the experiments shown was up to 2.7 log₁₀ FFU/ml, indicated by y-axis break. *, at this time point, the experiment consisted only of replicate cultures maintained in DMEM + 10% FBS; only one culture was titrated.