The present invention relates to a recombinant HBV cccDNA comprising HBV genome or the fragment or variant thereof and a site-hybrid insert, a method to generate said recombinant HBV cccDNA, a method for establishment of an in vitro or in vivo cccDNA based model for persistently hepatitis B virus replication by using the recombinant HBV cccDNA of the present invention, and a method for anti-HBV drug evaluation.

The present invention relates to methods and uses for screening anti-hepadnaviral substances, wherein the substances are screened for the capacity to inhibit covalently closed circular (ccc) DNA of a hepadnavirus, like hepatitis B virus. The methods and uses take advantage of cells comprising a nucleic sequence encoding a tagged hepadnavirus e antigen, like Hepatitis B virus e antigen (HBeAg). Furthermore, the present invention provides nucleic acid sequences encoding a tagged hepadnavirus e antigen and proteins encoded thereby. Also kits for use in the screening methods are provided.

The invention provides a recombinant polypeptide comprising the EDIII domain of each of Dengue virus serotype DENV-1, DENV-2, DENV-3, and DENV-4 linked to the N-terminal of HBsAg.

This disclosure describes a method to induce HBV infection in cells or animal models with an HBV pregenomic RNA (pgRNA). The method is amenable to multiple genotypes and has excellent signal-to-noise ratios. The method can be used to identify novel anti-HBV agents, measure anti-HBV drug efficiency, and predict drug resistance.

Disclosed herein are methods for producing virus-infected cell lines or animal models, wherein an enveloped virus including a lipid bilayer is mixed with a bile acid or a bile acid derivative, which allows the lipid bilayer to be replaced with a lipid bilayer derived from a target animal. Also disclosed herein are the virus-infected cell lines or animal models so produced and methods of screening a therapeutic candidate for a viral disease using the same.

The present invention is directed to a method of manufacturing a polyepitopic protein comprising the steps of cloning a blunt-ended DNA sequence by encoding the epitope that is to be cloned into a DNA vector recognized by the endonuclease Small or the endonuclease Sapl and isolating the polyepitopic protein by transforming a bacterial host cell with such vector, as well as a DNA vector for embodying this method.

The invention provides a recombinant polypeptide comprising the EDIII domain of each of Dengue virus serotype DENV-1, DENV-2, DENV-3, and DENV-4 linked to the N-terminal of HBsAg.

A method for separating virus-like particles from a cell suspension of host cells. The virus-like particles having at least one envelope protein embedded in a lipid double membrane including at least a portion corresponding to a small envelope protein of a virus of the family Hepadnaviridae. The host cells are disrupted to obtain a first suspension. A supernatant containing the virus-like particles is separated from the first suspension. Then, an adsorbent is added to the supernatant and separated off. Then, the virus-like particles are desorbed from the adsorbent by adding a desorption buffer. A soluble calcium salt is added to a supernatant separated from the second suspension to form a precipitate, the precipitate formed is separated off and transferred to a third suspension. The virus-like particles are separated from the third suspension and purified.

The present invention is directed to a method of manufacturing a polyepitopic protein comprising the steps of cloning a blunt-ended DNA sequence by encoding the epitope that is to be cloned into a DNA vector recognized by the endonuclease SmaI or the endonuclease SapI and isolating the polyepitopic protein by transforming a bacterial host cell with such vector.

The invention provides a recombinant polypeptide comprising the EDIII domain of each of Dengue virus serotype DENV-1, DENV-2, DENV-3, and DENV-4 linked to the N-terminal of HBsAg.