HBV cccDNA in patients' sera as an indicator for HBV reactivation and an early signal of liver damage

摘要

AIM: To evaluate the covalently closed circle DNA (cccDNA) level of hepatitis B virus (HBV) in patients' liver and sera. METHODS: HBV DNA was isolated from patients' liver biopsies and sera. A sensitive real-time PCR method, which is capable of differentiation of HBV viral genomic DNA and cccDNA, was used to quantify the total HBV cccDNA. The total HBV viral DNA was quantitated by real-time PCR using a HBV diagnostic kit (PG Biotech, LTD, Shenzhen, China) described previously. RESULTS: For the first time, we measured the level of HBV DNA and cccDNA isolated from ten HBV patients' liver biopsies and sera. In the liver biopsies, cccDNA was detected from all the biopsy samples. The copy number of cccDNA ranged from from 0.03 to 173.1 per cell, the copy number of total HBV DNA ranged from 0.08 to 3 717 per cell. The ratio of total HBV DNA to cccDNA ranged from 1 to 3 406. In the sera, cccDNA was only detected from six samples whereas HBV viral DNA was detected from all ten samples. The ratio of cccDNA to total HBV DNA ranged from 0 to 1.77%. To further investigate the reason why cccDNA could only be detected in some patients' sera, we performed longitudinal studies. The cccDNA was detected from the patients' sera with HBV reactivation but not from the patients' sera without HBV reactivation. The level of cccDNA in the sera was correlated with ALT and viral load in the HBV reactivation patients. CONCLUSION: HBV cccDNA is actively transcribed and replicated in some patients' hepatocytes, which is reflected by a high ratio of HBV total DNA vs cccDNA. Detection of cccDNA in the liver biopsy will provide an end-point for the anti-HBV therapy. The occurrence of cccDNA in the sera is an early signal of liver damage, which may be another important clinical parameter.