Hepatitis B RNA and Core-Related Antigen Provide Value Beyond DNA in Evaluating e But Not Surface Antigen Clearance

Biogenesis of serum HBV RNA and clinical phenomena of serum HBV RNA in chronic hepatitis B patients before and after receiving nucleos(t)ide analogues therapy

There are estimated 300 million people afflicted with chronic hepatitis B (CHB) worldwide. The risk of liver cirrhosis and hepatocellular carcinoma (HCC) increases considerably with chronic hepatitis B infection. While current therapeutics are effective in controlling hepatitis B virus (HBV) infection and disease progression, a cure for HBV infection remains unattainable due to an intranuclear replicative intermediate known as covalently closed circular DNA (cccDNA). It has recently been shown that serum HBV RNA is a non-invasive biomarker that reflects cccDNA transcriptional activity. This review provides a comprehensive overview and the latest updates on the molecular characteristics and clinical significance of serum HBV RNA, such as species of serum HBV RNA, forms of serum HBV RNA carriers and predictive value for relapses in CHB patients after nucleos(t)ide analogues (NAs) discontinuation and development of liver fibrosis and HCC. Furthermore, we summarize standardized assays for testing serum HBV RNA, the dynamic changes of serum HBV RNA levels in treatment-naïve CHB patients and those under NAs therapy, as well as the host and viral influencing factors of serum HBV RNA levels. Finally, we discuss the future perspectives in studies of serum HBV RNA.

Quantification of circulating HBV RNA expressed from intrahepatic cccDNA in untreated and NUC treated patients with chronic hepatitis B

OBJECTIVE

A convenient, reproducible biomarker of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) transcriptional activity is lacking. We measured circulating HBV RNA (cirB-RNA) in untreated and nucleos(t)ide analogues (NUC) treated chronic hepatitis B (CHB) patients to define its correlation with intrahepatic viral markers and HBV core-related antigen (HBcrAg).

DESIGN

Paired liver biopsy and serum samples were collected from 122 untreated and 30 NUC-treated CHB patients. We measured cirB-RNA, HBV DNA, hepatitis B surface antigen (HBsAg), HBcrAg and alanine aminotransferase levels. cirB-RNA was quantified using an investigational HBV RNA assay for use on the cobas 6800 system. The test detects a region spanning the HBV canonical polyadenylation site. cccDNA and 3.5 kb RNA in liver tissue were assessed by quantitative PCR and droplet digital PCR.

RESULTS

cirB-RNA was detectable in 100% of HBeAg(+) chronic hepatitis (CH), 57% and 14% of HBeAg(-) CH and chronic infection untreated patients and 47% of NUC-treated patients. cirB-RNA undetectability was associated with lower intrahepatic cccDNA transcriptional activity, as well as serum HBcrAg, but no significant differences in HBsAg, in both untreated and treated patients. In untreated HBeAg(-) patients, cirB-RNA correlated with intrahepatic 3.5 kb RNA and cccDNA transcriptional activity, serum HBV DNA and HBcrAg, but not with HBsAg or total cccDNA levels. Combined undetectability of both cirB-RNA and HBcrAg detection in untreated HBeAg(-) patients identified a subgroup with the lowest levels of intrahepatic transcriptionally active cccDNA.

CONCLUSION

Our results support the usefulness of quantification of circulating HBV RNA expressed from cccDNA as an indicator of intrahepatic active viral reservoir in both untreated and NUC-treated CHB patients.

TRIAL REGISTRATION NUMBER

NCT02602847.