Potential capacity of interferon-α to eliminate covalently closed circular DNA (cccDNA) in hepatocytes infected with hepatitis B virus

Interferon-alpha (IFN-α) and nucleot(s)ide analogs (NAs) are first-line drugs for the treatment of chronic hepatitis B virus (HBV) infections. Generally, NAs target the reverse transcription of HBV pregenomic RNA, but they cannot eliminate covalently-closed-circular DNA (cccDNA). Although effective treatment with NAs can dramatically decrease HBV proteins and DNA loads, and even promote serological conversion, cccDNA persists in the nucleus of hepatocytes due to the lack of effective anti-cccDNA drugs. Of the medications currently available, only IFN-α can potentially target cccDNA. However, the clinical effects of eradicating cccDNA using IFN-α in the hepatocytes of patients with HBV are not proficient as well as expected and are not well understood. Herein, we review the anti-HBV mechanisms of IFN-α involving cccDNA modification as the most promising approaches to cure HBV infection. We expect to find indications of promising areas of research that require further study to eliminate cccDNA of HBV in patients.

Hepatitis B Virus Covalently Closed Circular DNA Predicts Postoperative Liver Cancer Metastasis Independent of Virological Suppression

New antiviral therapies against hepatitis B virus (HBV) focus on the elimination of covalently closed circular DNA (cccDNA). However, traditional cccDNA-specific quantitative PCR (qPCR) has a narrow effective range, hindering a reliable comparison between the levels of biopsy-derived cccDNAs. Collaterally, the prognostic role of cccDNA in HBV-related hepatocellular carcinoma (HCC) cannot be clearly defined. Here, we developed a peptide nucleic acid (PNA)-clamping qPCR method to provide a wider range of specific cccDNA quantification (up to 5 logs of effective range). Extrachromosomal DNA was extracted from para-neoplastic tissues for cccDNA quantification. In total, 350 HBV-related HCC patients were included for an outcome analysis. Without differential pre-dilution, cccDNA levels in para-neoplastic liver tissues were determined, ranging from < 2 × 103 to 123.0 × 106 copies/gram. The multivariate linear regression analysis showed that cccDNA was independently correlated with the HBV e antigen (p < 0.001) and serum HBV-DNA levels (p = 0.012). The Cox proportional hazard model analysis showed that cccDNA independently predicted overall survival (p = 0.003) and extrahepatic metastasis-free survival (p = 0.001). In virologically suppressed HCC patients, cccDNA still effectively predicted intrahepatic recurrence-free (p = 0.003) and extrahepatic metastasis-free (p = 0.009) survivals. In conclusion, cccDNA independently predicted postoperative extrahepatic metastasis-free survival.