FIG. 4.

Poliovirus growth and error accumulation during serial passage in RBV-sensitive and RBV-resistant cell lines. RBV-sensitive HeLa, RBV-sensitive Huh-7, or RBV-resistant cured pool 4 cells were infected with poliovirus at an MOI of 10 PFU per cell in the presence or absence of 800 μM RBV. (A) Resulting amounts of virus (PFU per cell) are shown as a function of passage number. Pass 3 for HeLa cells was not performed due to low virus titer in the 800 μM RBV sample from pass 2. Open squares, 0 μM RBV; black squares, 800 μM RBV; ND, not done; passage numbers are indicated below the graphs in panel B. (B) Error accumulation upon passage. Guanidine resistance frequencies of poliovirus progeny from each passage are shown for HeLa, Huh-7, and cured pool 4 cells. The PFU per milliliter on plates containing 0.5 mM guanidine was divided by the PFU per milliliter on plates lacking guanidine to determine an estimate of the error frequency. Clear bars, 0 μM RBV; black bars, 800 μM RBV.