Department of Medicine, Seoul National University Bundang Hospital, Seongnam, South
Intervirology. 2011;54(6):316-25. doi: 10.1159/000321450. Epub 2011 Jan 14.
The aim of this study was to examine the methylation status of intrahepatic hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) and to elucidate the possible relationship between the cccDNA methylation and viral replicative activity in patients with HBV-related liver cirrhosis (HBV-LC).
The methylation status of HBV cccDNA was investigated by bisulfite sequencing in nonneoplastic tissues from 12 patients with HBV-LC who underwent surgical resection for combined hepatocellular carcinoma. Clinical, biochemical and virologic factors were evaluated with respect to the degrees of cccDNA methylation. We also examined the effect of methylation of cccDNA on viral transcription by an in vitro transcription assay.
Variable degrees of CpG methylation were present in the HBV cccDNA from patients with HBV-LC. Old age, low serum HBV DNA levels and low virion productivity were significantly associated with elevated cccDNA methylation. Virion productivity of cccDNA was also lower in HepAD38 cells with a higher degree of cccDNA methylation. In vitro transcription assays showed that the transcriptional activity of HBV cccDNA was suppressed by increased methylation of cccDNA.
Increased CpG methylation of cccDNA is associated with old age, low serum HBV DNA levels and suppressed replicative activity in HBV-LC.
本研究旨在检测乙型肝炎病毒（HBV）cccDNA 的甲基化状态，并阐明 HBV 相关肝硬化（HBV-LC）患者 cccDNA 甲基化与病毒复制活性之间的可能关系。
对 12 例因合并肝细胞癌而行手术切除的 HBV-LC 患者的非肿瘤组织进行亚硫酸氢盐测序，以检测 HBV cccDNA 的甲基化状态。评估 cccDNA 甲基化程度与临床、生化和病毒学因素的关系。我们还通过体外转录实验研究了 cccDNA 甲基化对病毒转录的影响。
HBV-LC 患者的 HBV cccDNA 存在不同程度的 CpG 甲基化。高龄、血清 HBV DNA 水平低和病毒粒子产量低与 cccDNA 高甲基化显著相关。cccDNA 甲基化程度较高的 HepAD38 细胞中病毒粒子的产量也较低。体外转录实验表明，cccDNA 的甲基化增加抑制了 HBV cccDNA 的转录活性。
HBV-LC 中 cccDNA 的 CpG 甲基化增加与高龄、血清 HBV DNA 水平低和复制活性受抑制有关。
