Fig. 2.

HCV pseudovirus entry into human cell lines. (A) Cells (10⁴) indicated along the x axis were infected with NLluc⁺env^- viruses (≈100 ng/ml p24) pseudotyped with no envelope glycoproteins, E1/E2, or E1/E2 coexpressed with p7, and luciferase activities (r.l.u.) were measured 48 h postinfection. Results are means of three independent experiments ± SD. (B) Alternatively, Huh-7 cells (10⁴) were premixed with control murine IgG1 (10 μg/ml), sera (1:100) from two HCV^- and two HCV 1a⁺ donors, or mAbs A4 (anti-E1), H53 (anti-E2), 091b (anti-E2), or JS-81 (anti-CD81) (each at 10 μg/ml), immediately followed by infection with NLluc⁺env^- viruses (≈100 ng/ml p24) pseudotyped with E1/E2. Luciferase activities (r.l.u.) were measured 48 h postinfection and standardized for p24 content. The % pseudovirus entry was calculated by (r.l.u. in the presence of inhibitor)/(r.l.u. in the absence of inhibitor) × 100%. Results are from a representative experiment with an assay error of ±25%. Low levels of inhibition observed with anti-E2 mAb H53 (10 μg/ml) were within the error of the assay. (C) 3T3, HepG2, as well as CD81⁺ derivatives thereof were infected with NLluc⁺env^- viruses (≈100 ng/ml p24) pseudotyped with no envelope glycoproteins, E1/E2, or E1/E2 coexpressed with p7, and luciferase activities (r.l.u.) were measured 48 h postinfection. Results are means of three independent experiments ± SD.