Requirement of Activation for Hepatitis B Virus Infection

Although _in vitro_ models of human hepatitis B virus replication are established, so far none could approximate infection efficiency as expected from _in vivo_ observations. Susceptibility for HBV infections has only been reported for primary hepatocytes of human, chimpanzee or Tupaia belangeri and the cell line HepaRG. Here we show that the insusceptible human hepatoma cell line HepG2 can be infected, when the virus was beforehand activated by passage over whole duck liver cell cultures. That suggests an activation step to be performed by specialized liver cells.