Expression of HBV envelope and nucleocapsid proteins in human cells using vaccinia virus vectors

We have analysed the expression of HBV envelope (large, middle, major) and nucleocapsid (core and precore) proteins in human skin fibroblasts and Epstein-Barr virus-transformed human B-cell lines infected with recombinant vaccinia virus vectors. The large envelope protein was not secreted and barely detectable in the cytosol, whereas middle s and major s where both water soluble and efficiently secreted in abundant quantities. The precore polypeptide was also secreted whereas the core protein was totally retained within a water soluble intracellular compartment, thus confirming the presence of a signal peptide within the precore region responsible for targeting the protein to the endoplasmic reticulum for excretion. It is anticipated that such recombinants will provide a useful tool for analysis of HBV-specific cytolytic T lymphocytes.