HDAC1 and hepatocellular carcinoma: Studies in hepatoma cell lines have shown that cccDNA transcription is regulated by the acetylation status of cccDNA-bound histones 3 and 4 (H3 and H4), while data obtained from liver biopsies of HBV-infected patients indicated that histone hypoacetylation and histone deacetylase 1 (HDAC1) recruitment onto the cccDNA correlate with low HBV viremia [71].