Evidence for long-term association of virion-delivered HBV core protein with cccDNA independently of viral protein production

Julie Lucifora; Florentin Pastor; Émilie Charles; Caroline Pons; Héloïse Auclair; Floriane Fusil; Michel Rivoire; François-Loïc Cosset; David Durantel; Anna Salvetti

doi:10.1016/j.jhepr.2021.100330

Evidence for long-term association of virion-delivered HBV core protein with cccDNA independently of viral protein production

JHEP Rep. 2021 Jul 8;3(5):100330. doi: 10.1016/j.jhepr.2021.100330. eCollection 2021 Oct.

Authors

Affiliations

¹ CIRI - Centre International de Recherche en Infectiologie, Univ Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, F-69007 Lyon, France.
² Past affiliation: INSERM, U1052, Cancer Research Center of Lyon (CRCL), University of Lyon (UCBL1), CNRS UMR_5286, Centre Léon Bérard, Lyon, France.
³ INSERM U1032, Centre Léon Bérard (CLB), Lyon, France.

Abstract

Background & aims: HBV persists in the nucleus of infected hepatocytes as a covalently closed circular DNA (cccDNA) episome that constitutes the template for viral RNA and protein synthesis. Both HBx and HBc (core) viral proteins associate with cccDNA but, while HBx is required for viral transcription, the role of HBc is still unclear. The aim of this study was to determine if HBc derived from incoming nucleocapsid can associate with cccDNA before the onset of viral transcription and protein production.

Methods: Chromatin immunoprecipitation assays were performed in native conditions. In addition, differentiated HepaRG (dHepaRG) cells infected with HBx-deficient HBV were used to investigate if HBc delivered by incoming virions can associate with cccDNA.

Results: Our results indicate that HBc can associate with cccDNA in the absence of viral transcription and de novo protein synthesis. In dHepaRG cells, this association is stable for at least 6 weeks.

Conclusion: These results suggest that virion-delivered HBc may participate at an early stage of cccDNA formation and/or transcription.

Lay summary: The hepatitis B virus genome is released into the nucleoplasm of infected cells after disassembly of the viral nucleocapsids at the nuclear membrane. Herein, we show for the first time that virion-delivered hepatitis B core protein, a component of the viral capsid, can stably associate with integrated viral DNA.

Keywords: CAM; ChIP; ChIP, chromatin immunoprecipitation; FA, formaldehyde; H3K27Ac, histone 3 lysine 27 acetylation; HBVΔX, HBx-deficient HBV; HBc; HBc, HBV core protein; Hepatitis B Virus; HuHep, liver-humanized mice; PHHs, primary human hepatocytes; cccDNA; cccDNA, covalently closed circular DNA; dHepaRG, differentiated HepaRG cells; rcDNA, relaxed circular DNA.