PROS1 and infection: To assess whether nonproductive HBV transcription from cccDNA can be reactivated, we conducted cell culture experiments in which we infected HepG2-NTCP cells with different recombinant viruses: wild-type HBV (HBV-WT); HBV-ΔX, which is transcriptionally inactive upon infection and does not express core or S protein; and HBV-ΔC, which is transcriptionally active upon infection and expresses S but not core protein (Fig. 7A and C).