Figure 6.

Challenge of the transfected woodchucks with WHV7. At 24 weeks after transfection, selective woodchucks were challenged with a 10⁷ infectious dose of serum-derived WHV7. Serological markers were tested biweekly from 4 weeks before challenge (weeks –4 and –2) to 12 weeks after challenge. Time 0 with an arrow represents the time of challenge. The serologic profiles of some of the challenged animals are shown. Signal-to-noise (mean OD of three serum samples of the animal before intrahepatic inoculation) ratio (S/N) for each serologic assay is shown. S/N greater than 3 is considered positive. Serum WHV DNA was assayed as described in Methods, and duplicate assays were performed independently for each serum sample. Only samples positive for both assays were scored as positive. For sample with only one positive assay, a third was performed; if the third was positive, the sample was scored as positive.