Hepatitis B virus cccDNA is formed through distinct repair processes of each strand. Author Lei Wei, Alexander Ploss Publication Year 2021 Type Journal Article Abstract Hepatitis B virus (HBV) is a highly contagious pathogen that afflicts over a third of the world's population, resulting in close to a million deaths annually. The formation and persistence of the HBV covalently closed circular DNA (cccDNA) is the root cause of HBV chronicity. However, the detailed molecular mechanism of cccDNA formation from relaxed circular DNA (rcDNA) remains opaque. Here we show that the minus and plus-strand lesions of HBV rcDNA require different sets of human repair factors in biochemical repair systems. We demonstrate that the plus-strand repair resembles DNA lagging strand synthesis, and requires proliferating cell nuclear antigen (PCNA), the replication factor C (RFC) complex, DNA polymerase delta (POLδ), flap endonuclease 1 (FEN-1), and DNA ligase 1 (LIG1). Only FEN-1 and LIG1 are required for the repair of the minus strand. Our findings provide a detailed mechanistic view of how HBV rcDNA is repaired to form cccDNA in biochemical repair systems. Keywords Humans, Cell Line, Tumor, Virus Replication, Hepatitis B virus, DNA, Viral, DNA Replication, DNA Repair, Proliferating Cell Nuclear Antigen, Hepatitis B, Chronic, Hep G2 Cells, DNA Polymerase III, DNA Ligase ATP, DNA, Circular, Flap Endonucleases, Replication Protein C Journal Nat Commun Volume 12 Issue 1 Pages 1591 Date Published 2021 Mar 11 ISSN Number 2041-1723 DOI 10.1038/s41467-021-21850-9 Alternate Journal Nat Commun PMCID PMC7952586 PMID 33707452 PubMedPubMed CentralGoogle ScholarBibTeXEndNote X3 XML