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.