For in vitro assay, there several cell lines that can be transfected with replication-competent plasmid. Then viral replication fitness can be assessed. Many investigator use Huh7 and transfect this cell with the replication-competent HBV vector. Viral infection can be measured within different steps, as detecting HBV RNAs, pregenomic RNAs, Viral DNA and markers (HBsAg) in cell culture supernatant and detection of Progeny HBV DNA. Each of then can tell you the component potentially inhibit which step of HBV life cycle as transcription, progeny capsid formation, viral egress and so on.
Of note, you should be take care of potential toxicity of the component on cells before doing real experiment. See these papers that may give you more information about in vitro assay:
Unlike HCV, there is no good cell culture model for HBV. Besides Samad's suggestions, I would like to add Ready Heps Fresh Human Hepatocytes, which now are available from a lot of commercial companies.
If you find one please keep me abreast!! it depends on your subject. for a comparing the replication efficincy of virus after certian cycles, transfection is not recommended. for infection, nobody until now has found a perfect cell line. Personally I used FTO.9.1 cell line. I was happy by thi scell line. however, globally people use HepG2.215. you could read my article: Propagation of Hepatitis B Virus in a Rat Hepatoma Cell Line Stably Transfected with Human Annexin-V-Hepatitis Monthly 2007; 7(3): 143-147.