The invention provides inducible promoter systems and their components incorporating components of a tetracycline operon. By coordinating expression of different transcriptional units in these systems as a result of selection of promoters and/or linking the units into the same DNA molecule, these systems can achieve higher levels of expression of coding segments of interest, increased differential levels of expression between on- and off-states, and/or greater responsiveness to inducing agents than conventional systems.

The invention provides inducible promoter systems and their components incorporating components of a tetracycline operon. By coordinating expression of different transcriptional units in these systems as a result of selection of promoters and/or linking the units into the same DNA molecule, these systems can achieve higher levels of expression of coding segments of interest, increased differential levels of expression between on- and off-states, and/or greater responsiveness to inducing agents than conventional systems.

The invention provides inducible promoter systems and their components incorporating components of a tetracycline operon. By coordinating expression of different transcriptional units in these systems as a result of selection of promoters and/or linking the units into the same DNA molecule, these systems can achieve higher levels of expression of coding segments of interest, increased differential levels of expression between on- and off-states, and/or greater responsiveness to inducing agents than conventional systems.

The present disclosure relates to isolated polynucleotides and polypeptides, and related hepatitis B virus (HBV)vaccines. The present disclosure also relates to viral vectors for expressing such polypeptides, and which may be used in HBV vaccines, as well as methods of protecting a subject from HBV infection and methods of treating HBV in a subject comprising administering the polypeptides, vectors, or vaccines described herein. Methods of designing and producing an HBV vaccine comprising designing vaccine antigens to cover the diversity within a geographic area using an antigen amino acid sequence that efficiently covers the epitopes in the HBV genotypes present in the geographic area are also provided herein.

The invention provides inducible promoter systems and their components incorporating components of a tetracycline operon. By coordinating expression of different transcriptional units in these systems as a result of selection of promoters and/or linking the units into the same DNA molecule, these systems can achieve higher levels of expression of coding segments of interest, increased differential levels of expression between on- and off-states, and/or greater responsiveness to inducing agents than conventional systems.

Isolated polynucleotides and polypeptides, and hepatitis B virus (HBV) vaccines comprising the same. Viral vectors for expressing such polypeptides, and which may be used in HBV vaccines, as well as methods of protecting a subject from HBV infection and methods of treating HBV in a subject comprising administering the polypeptides, vectors, or vaccines. Methods of designing and producing an HBV vaccine comprising designing vaccine antigens to cover the diversity within a geographic area using an antigen amino acid sequence that efficiently covers the epitopes in the HBV genotypes present in the geographic area.