HCV can associate with B cells and transinfect hepatoma cells. (A) PBMC-derived primary B cells, Burkitt lymphoma B-cell lines L3055-Bcl-2 and KEM, and Huh-7.5 hepatoma cells were allowed to bind JFH-1 for 2 hours on ice. HCV RNA copy numbers were determined by quantitative RT-PCR, and the fold change in HCV RNA was defined after 72 hours. Error bars represent the SD from 3 or 4 replicates. (B) Cartoon depicting the protocol for measuring B-cell transinfection of Huh-7.5 cells. The image depicts a group of NS5A⁺ (green) infected Huh-7.5 cells, which are designated as FFUs. The Huh-7.5 cell monolayer and remaining B cells were visualized by DAPI, staining their large oval and small round nuclei, respectively. (C) Increasing numbers of PBMC-derived purified B cells and the corresponding B cell–depleted fraction, L3055–Bcl-2, or KEM were incubated with JFH-1 and cocultured with Huh-7.5 cells. Data represent the FFU in Huh-7.5 cells per stated number of cocultured lymphoid cells. (D) Effect of CD40L and IL-4 stimulation on PBMC-derived B cell (8 blood donors; BD1-8), L3055–Bcl-2 or KEM cell JFH-1 transinfection of Huh-7.5 cells. Resting () and CD40L/IL-4–stimulated (□) cells are depicted. (E) CD40L/IL-4–stimulated PBMC and liver-derived B cells from 2 HCV-infected patients (P1 and P2) can transinfect Huh-7.5 cells with JFH-1. Error bars represent the SEM from 3 replicate infections.