Host factor PRPF31 is involved in cccDNA production in HBV-replicating cells

Area of Science:

• Virology
• Molecular Biology
• Hepatology

Background:

• Chronic Hepatitis B virus (HBV) infection is sustained by covalently closed circular DNA (cccDNA).
• Current antiviral therapies effectively suppress HBV replication but fail to eliminate cccDNA, hindering complete treatment endpoints.
• Novel therapeutic strategies targeting cccDNA are crucial for eradicating chronic HBV.

Purpose of the Study:

• To identify host factors involved in the formation of HBV cccDNA.
• To evaluate the potential of targeting identified factors for anti-HBV therapy.

Main Methods:

• siRNA screening to identify host factors associated with cccDNA.
• siRNA-mediated knockdown of PRPF31 and subsequent assessment of cccDNA levels.
• Rescue experiments using siRNA-resistant PRPF31.
• Chromatin immunoprecipitation and immunoprecipitation assays to investigate PRPF31-cccDNA interaction.
• Co-expression studies with PRPF31 and HBx in HBV-replicating cells.

Main Results:

• siRNA screening identified pre-mRNA processing factor 31 (PRPF31) as a factor associated with cccDNA formation.
• PRPF31 knockdown significantly decreased cccDNA formation with minimal cytotoxicity.
• Rescue experiments confirmed PRPF31's role in cccDNA formation.
• PRPF31 knockdown did not impact HBV core protein or HBV core DNA levels.
• Evidence of an association between PRPF31 and cccDNA was established through ChIP and IP assays.
• Co-overexpression of PRPF31 and HBx enhanced cccDNA formation.

Conclusions:

• PRPF31 is a novel host factor that promotes HBV cccDNA formation.
• The interaction between PRPF31 and HBx may play a significant role in cccDNA maintenance.
• Targeting the PRPF31-HBx interaction presents a potential new therapeutic strategy for eliminating cccDNA in chronic HBV infection.