Provided herein are engineered hepatitis B virus (HBV) molecular vaccine constructs. Vaccine constructs can also include ligand-inducible engineered gene switch systems for modulating expression of heterologous genes, such as a cytokines, in host cells.

The present disclosure provides compositions and methods useful for inducing a The cell response in a subject suffering from Hepatitis B. As described herein, the compositions of the disclosure comprise HBsAg having S, Pre-S1 and Pre-S2 proteins and an aluminum phosphate adjuvant. In a preferred embodiment, the immunogenic composition comprises at least 20 μg/ml of HBsAg antigen and the amount of non-adsorbed antigen is at least 30%.

Chimeric genes, compositions of chimeric genes, and compositions of polypeptides that are useful for the generation, enhancement, or improvement of an immune response to a target antigen. Some embodiments of the compositions include chimeric genes encoding hepatitis D antigen (HDAg) protein in combination with one or more self-cleavage 2A polypeptides and a preS1 polypeptide. In certain embodiments the self-cleavage polypeptide is P2A.

Embodiments described herein provide orthohepadnavirus capsid protein (Cp) heterodimers, bicistronic vectors encoding the heterodimers, and methods for producing the heterodimers. The heterodimers can be used to form mosaic virus-like particles. In certain embodiments, the heterodimers can form a hexamer, which in turn can be used to nucleate capsid formation, resulting in a Janus particle-like virus-like particle. The hexamer's can then be removed, leaving holey capsids. The capsids can be loaded with, for example, one or more polypeptides, small molecules, or a combination of polypeptides and small molecules. The holes of the holey capsids can be filled with another orthohepadnavirus heterodimer or a homodimer.

The invention provides a novel fusion protein between flagellin (or portions thereof) and a polypeptide that can form a virus-like particle (VLP) (e.g., hepatitis b core (HBc) protein or portions thereof), where the fusion protein continues to form a VLP in an aqueous environment. The VLPs based on such fusion proteins (e.g., FH VLPs) provide a versatile, highly immunogenic, and safe vaccine carrier capable of displaying or associating a variety of vaccine antigens on VLP surface to elicit potent humoral and cellular immune responses.

The present invention provides a virus-like particle comprising several or more types of HBs-L antigen proteins or a virus-like particle composition comprising a combination of the virus-like particles, for the purpose of provision of an antigen that triggers an immune reaction against HBV of various genotypes.

The disclosure provides compositions and methods of treating a metabolic disease, such as, e.g., diabetes and hyperlipidemia, in a subject, by administering to the subject a therapeutically effective amount of a polypeptide derived from hepatitis B virus or a pharmaceutical composition comprising the polypeptide.

The present invention provides novels method of targeting delivery of a compound to hypoxic cells, for example treatment of diseases and disorders associated with hypoxia, comprising administration of a construct comprising a targeting carrier peptide and a compound for delivery to a hypoxic cell. The invention also provides novel methods for the treatment of diseases or disorders of the eye by administration of a novel construct, a nucleic acid encoding a novel construct, and/or a nucleic acid vector comprising a nucleic acid encoding a novel construct. The invention further provides novel constructs, nucleic acids encoding such constructs, and/or nucleic acid vectors comprising nucleic acids encoding such constructs.

Provided herein are non-naturally occurring variants of the hepatitis B virus (HBV) Core protein, the HBV polymerase N-terminal domain, and the HBV polymerase C-terminal domain, as well as immunogenic fragments thereof. Fusion proteins comprising the HBV variants fused to a herpes simplex virus (HSV) glycoprotein (gD) sequence, as well as methods of using the fusion proteins, are also provided.

Severe Acute Respiratory Syndrome Coronavirus 2 antigen virus-like particles (VLPs) and recombinant immune complexes (RICs) are described, along with methods of making said VLPs and RICs in plants and using said VLPs and RICs to induce an immune response in a subject.