Fig 1.

Schematic representation of the experimental protocol applied to infect and challenge woodchucks with multiple small, liver-nonpathogenic doses of WHV. Four WHV-naïve animals were i.v. injected at weekly intervals with 6 doses of 1.1 × 10² virions each of WHV/tm3 inoculum (round 1). Thirty weeks after the first virus injection (infection phase), the animals were challenged with another 6 weekly doses of 1.1 × 10² virions each of the same inoculum (round 2). Thirteen weeks following the completion of round 2 (challenge phase), the animals were rechallenged with 1.1 × 10⁶ virions of WHV/tm3 inoculum or injected with 0.5 ml of sterile PBS and followed for up to 75 weeks after the first virus injection (rechallenge phase).