Adaptation of Hepatitis C Virus to Mouse CD81 Permits Infection of Mouse Cells in the Absence of Human Entry Factors
Figure 4
Efficiency of human CD81 usage by Jc1 and Jc1 variants.
(A) Neutralization with antibodies specific for human CD81: Indicated viruses (luciferase reporter viruses) were mixed with different concentrations of the human CD81-specific monoclonal antibodies 5A6 or 1.3.3.22. Alternatively, viruses were mixed with CD13-specific control antibodies. Subsequently, mixtures were used to inoculate Lunet N hCD81 cells. Infectivity was determined and expressed as described in the legend of figure 3. (B) Determination of the threshold level of CD81 needed for infection: Naïve Huh7-Lunet cells were mixed with Lunet N hCD81 cells in a ratio of 1∶1 and were infected with indicated Venus Jc1 reporter viruses normalized for equal amounts of core protein. 72 h after infection the cells were harvested, fixed and stained for CD81 with the CD81 specific antibody 5A6 and a secondary antibody coupled to APC. The Venus GFP signal was plotted against the CD81 expression and the percentage of HCV infected cells at a given CD81 cell surface expression was calculated. The graph displays the percentage of HCV infected cells as a function of CD81 expression level plotted as mean fluorescence intensity (MFI). A representative experiment carried out in duplicates is given. Dashed lines indicate the turning points of the individual curves. FACS dot plots of the experiment are shown as supplementary figureS4.