CHD4 promotes hepatitis B virus transcription by facilitating RNA polymerase II recruitment to cccDNA

Chronic hepatitis B virus (HBV) infection remains a major global health burden, largely due to the persistence of covalently closed circular DNA (cccDNA), which serves as the template for viral transcription. Although host factors involved in regulating cccDNA transcription have been increasingly recognized, the molecular mechanisms controlling HBV minichromosome activity remain incompletely understood. Chromodomain helicase DNA-binding protein 4 (CHD4), the catalytic component of the nucleosome remodeling and deacetylase (NuRD) complex, is a key regulator of chromatin remodeling and transcriptional regulation. In this study, we demonstrate that CHD4 facilitates efficient HBV transcription. Depletion of CHD4 in HBV-infected hepatoma cells markedly reduced viral RNA levels and antigen production without affecting HBV uptake, nuclear import, cccDNA establishment, or cccDNA stability. Mechanistically, CHD4 was recruited to HBV cccDNA and promoted the occupancy of RNA polymerase II (RNA Pol II) on the viral minichromosome. Loss of CHD4 impaired RNA Pol II recruitment to cccDNA, resulting in reduced viral transcription. Furthermore, domain mapping identified the CT2 region of CHD4 as essential for its interaction with RNA Pol II. Collectively, our findings reveal a previously unrecognized role of CHD4 in regulating HBV cccDNA transcription and establish CHD4-mediated RNA Pol II recruitment as a critical mechanism controlling HBV gene expression.IMPORTANCEHepatitis B virus (HBV) infection affects hundreds of millions of people worldwide and can lead to severe liver diseases, including cirrhosis and liver cancer. A major challenge in curing HBV infection is the persistence of a stable viral DNA structure inside infected liver cells that continuously produces viral components. Understanding how this viral DNA is controlled by host cells is essential for developing new therapeutic strategies. In this study, we identified chromodomain helicase DNA-binding protein 4 (CHD4) as a host factor that supports HBV gene production by helping the virus recruit the cellular machinery required for viral RNA synthesis. Our findings reveal a previously unrecognized mechanism by which human liver cells regulate HBV persistence and provide new insights into virus-host interactions that may guide future approaches to achieve durable HBV control.