FIG. 7.

Efficient HCV spread is impaired in cells expressing reduced apoB levels. apoB-deficient cells were infected at an MOI of 0.01 with JFH-1, and the infectivity in the cell supernatants was determined at different times postinfection. (A) apoB-deficient cells showed reduced apoB mRNA levels (black bars), as determined by RT-qPCR; reduced extracellular apoB levels (white bars), as determined by ELISA; and reduced HCV infectivity (gray bars) in the supernatants collected at day 7 postinfection. (B) Reduced cellular apoB levels lead to inefficient viral spread, as shown by the reduced numbers of infectious particles accumulated in the supernatant (FFU/ml) over time for cells expressing apoB shRNA-1 (white squares) and shRNA-3 (white triangles) compared to that for cells expressing GFP only (black diamonds). Results are presented as averages and standard deviations for duplicate experiments (n = 2). (C) apoB-deficient Huh-7 cells were infected at a low multiplicity (MOI of 0.01) with chimeric viruses expressing structural proteins from different genotypes. The reduced number of HCV core-positive cells at day 7 (JFH-1) or day 12 (J6, Con1, and H77) in apoB-deficient versus control cells suggests an inefficient viral spread in these cells, regardless of the genotype of the viral particles. (D) Infectivity titers at 7 days postinfection (FFU/ml) in the supernatants of cells infected at a low multiplicity reflect the reduced ability of cells expressing low apoB levels to produce infectious HCV particles from various HCV genotypes. Results are presented as percentages and are averages and standard deviations for triplicate experiments (n = 3).