FIG. 4.

HCV viremia after multigenotype challenge. HCV RNA was determined by quantitative real-time reverse transcription-PCR using chimpanzee plasma and the UGD assay. Dashed lines indicate the limit of detection (2.55 log₁₀ copies/ml). The last four samples were selected to confirm low titers or negativity of HCV RNA by using high-sensitivity PCR with a detection limit of 1.22 log₁₀ copies/ml as indicated by the dashed line, and the results are shown in the boxes on the chart.