FIG. 2.

Release of core protein and infectivity upon transfection of JFH1 constructs into Huh7-Lunet cells. (A) In vitro transcribed RNAs of JFH1 (black circles), Luc-JFH1 (black diamonds), and Luc-JFH1ΔE1-E2 (open squares) were transfected into Huh7-Lunet cells, and cell-free culture fluids were collected at 4 h to 96 h posttransfection. The amount of core protein present in the respective culture medium was determined employing a core-specific immunoassay (upper left graph). In parallel, supernatants were used to inoculate naïve Huh7-Lunet cells, and infectivity associated with the respective samples was quantified by using an immunofluorescence-based limiting dilution assay (upper right graph) and (where applicable) by assessing the amount of reporter activity present in target cells 72 h postinoculation (lower left graph). The gray lines indicate the background of the reporter assay from naïve Huh7-Lunet cells and the detection limit of the core ELISA, respectively. Mean values of two experiments are given; error bars represent standard errors of the means. (B) Huh7-Lunet cells were inoculated with serial dilutions of Luc-JFH1-containing medium or with undiluted Luc-JFH1/ΔE1-E2 culture fluid and lysed at the indicated time points postinoculation to quantify luciferase activity. Mean values of two independent wells are given (error bars show standard deviations). The gray line indicates the background of the assay determined by measuring mock-infected cells.