FIG 4.
Infectious progeny production of biological clones of hepatitis C virus passaged in the absence or presence of sofosbuvir. Biological clones and their parental populations are indicated in the upper boxes, and the absence or presence of sofosbuvir (SOF) is indicated at left. For the first passage, 4 × 105 Huh-7.5 reporter cells were infected with 1.2 × 104 TCID50 of the corresponding clone, to give a multiplicity of infection (MOI) of 0.03 TCID50/cell. For successive infections, 4 × 105 Huh-7.5 reporter cells were infected with the virus contained in 500 μl of the cell culture supernatant from the previous infection, yielding a range of MOIs of 1.25 × 10−5 to 7.9 TCID50/cell. Infections were allowed to proceed for 72 h. The abscissa axes indicate the limits of detection of virus titers. Procedures to obtain the biological clones and infection conditions are described in Materials and Methods.