Quantified integrated hepatitis B virus is related to viral activity in chronic hepatitis B patients

Background & Aims
The hepatitis B virus (HBV) can integrate in the host genome of the hepatocyte and recent findings suggest that integrated HBV contributes to the persistent production of viral proteins. Here we quantified the levels of integrated HBV in chronic hepatitis B (CHB) patients, and analysed the relation between HBV integration, virological activity (plasma HBV-DNA and HBsAg levels) and clinical outcomes.

Approach & Results
We developed and validated a multistep Alu-PCR that specifically amplifies integrated HBV and a RT-Alu-PCR detecting mRNA transcripts derived from integrated HBV. Pre-treatment liver biopsy samples and baseline characteristics of 124 CHB patients either treated for 48 weeks with Peg-IFN plus adefovir or tenofovir or received no treatment, were available for analysis. Integrated HBV sequences containing ORF S and X but not C, and S and X mRNA transcripts derived from integrated HBV could be detected and quantified in liver biopsies. Integrated HBV levels correlated with HBV DNA, HBsAg, ALT plasma levels and the liver histology activity index but not to levels of intrahepatic covalently closed circular (ccc)DNA, plasma pregenomic RNA or hepatitis B core-related antigen. Multivariable logistic regression analysis showed that lower baseline HBV integration levels were independently associated with HBsAg-loss (functional cure) within 5 years follow-up.

Integrated HBV levels are strongly correlated with surrogate markers for virological activity but not to cccDNA levels, and are predictive for HBsAg-loss. Our data suggest that integrated HBV is closely related to HBV replication and may therefore be an important tool in the evaluation and development of new treatment modalities aiming to cure CHB