The translocation motif of hepatitis B virus envelope proteins is dispensable for infectivity

The early events of hepatitis B virus (HBV) infection remain unclear. In 2006, Stoeckl et al. proposed a new entry mechanism involving a translocation motif (TLM) present in the pre-S2 domain of envelope proteins (L. Stoeckl, A. Funk, A. Kopitzki, B. Brandenburg, S. Oess, H. Will, H. Sirma, and E. Hildt, Proc. Natl. Acad. Sci. USA 103:6730-6734, 2006). After receptor binding and internalization into the endosomal compartment, this motif would allow the translocation of HBV particles through the endosomal membrane into the cytosol. In this study we have used two different mutated viruses containing a truncated TLM and showed their ability to infect human hepatocytes in primary culture, thus demonstrating the dispensability of the TLM for HBV infectivity.