Mapping of the Hepatitis B Virus Attachment Site by Use of Infection-Inhibiting preS1 Lipopeptides and Tupaia Hepatocytes

Background & aims: Studies on the early steps in the life cycle of hepatitis B virus have been hampered by the lack of readily available target cells. In this study, we mapped a defined virus attachment site to primary hepatocytes that is essential for infection. Methods: We used purified virus particles from human carrier plasma as an inoculum and primary cultures of tupaia hepatocytes as susceptible target cells and studied the inhibitory effect of amino-terminally acylated preS1-derived lipopeptides on infection interference. Results: Infectivity of virus could be blocked efficiently in this system by amino-terminally acylated peptides containing amino acids 2-18 from the preS1 domain. The addition of amino acids 28-48 enhanced the inhibitory capacity, whereas amino acids 49-78 did not contribute to inhibition. Myristoylated preS1 peptides 2-48 bound strongly to tupaia hepatocytes but not to nonhepatic cells or rodent hepatocytes and thereby inhibited infection even at concentrations of 1 nmol/L completely. Particles consisting only of the small hepatitis B surface protein-the active component of current hepatitis B vaccines-did not bind at all to tupaia hepatocytes, but the addition of the preS1 domain to the particles allowed binding. Conclusions: The preS1 sequence 2-48 mediates attachment of the virus to its target cells, whereas the small surface protein seems to be involved in other steps. These findings indicate that the current subunit hepatitis B vaccines may be improved by the addition of distinct preS1 epitopes. Moreover, preS1 lipopeptides are promising candidates for specific antiviral therapy against hepatitis B infections.