Guo Yanhai, Li Yongnian, Mu Shijie, Zhang Ju, Yan Zhen
State Key Laboratory of Cancer Biology, Department of Pharmacogenomics, School of Pharmacy, The Fourth Military Medical University, Xi'an, China.
J Med Virol. 2009 Jul;81(7):1177-83. doi: 10.1002/jmv.21525.
Epigenetic factors may modulate chronic Hepatitis B viral infection by affecting virion gene transcription. The aim of this study was to compare the methylation status of the intrahepatic covalently closed circular DNA (cccDNA) CpG island 2 and HBV replication capability. HBV cccDNA was extracted from liver biopsies of 55 HBsAg-positive patients with chronic hepatitis B (32 HBeAg-positive and 23 HBeAg-negative), and was analyzed for methylation status and quantity. The two Hpa II recognition sequences CCpGG in the CpG island 2 were methylated in infected liver tissues from 24 (43.6%) of 55 patients. Positive ratios of cccDNA methylation were significantly higher in HBeAg-negative patients (15/23, 65.2%) than HBeAg-positive patients (9/32, 28.1%) (P < 0.05). The percentage of methylated-cccDNA/total-cccDNA of HBeAg-negative samples (a median of 48%, ranging from 5% to 83%) was significantly higher (P < 0.001) than HBeAg-positive samples (a median of 14%, ranging from 0.26% to 35%). Ratios of relaxed circular DNA (rcDNA) to cccDNA molecules revealed that cccDNA methylation correlated with impaired virion productivity in HBeAg-positive individuals (P < 0.05). The bisulfite DNA sequencing showed that methylation density was significantly higher in HBeAg-negative than in HBeAg-positive patients (P < 0.05). The methylation level of the CpG island 2 of the cccDNA in HBeAg-negative patients was higher than that in HBeAg-positive patients, suggesting that HBV cccDNA methylation may be relevant to replication capability of HBV.
表观遗传因素可能通过影响病毒粒子基因转录来调节慢性乙型肝炎病毒感染。本研究的目的是比较肝内共价闭合环状DNA（cccDNA）CpG岛2的甲基化状态与乙肝病毒复制能力。从55例慢性乙型肝炎表面抗原（HBsAg）阳性患者（32例HBeAg阳性和23例HBeAg阴性）的肝活检组织中提取乙肝病毒cccDNA，并分析其甲基化状态和数量。55例患者中24例（43.6%）感染肝组织中CpG岛2的两个Hpa II识别序列CCpGG发生甲基化。HBeAg阴性患者中cccDNA甲基化阳性率（15/23，65.2%）显著高于HBeAg阳性患者（9/32，28.1%）（P<0.05）。HBeAg阴性样本中甲基化-cccDNA/总-cccDNA的百分比（中位数为48%，范围为5%至83%）显著高于HBeAg阳性样本（中位数为14%，范围为0.26%至35%）（P<0.001）。松弛环状DNA（rcDNA）与cccDNA分子的比例显示，cccDNA甲基化与HBeAg阳性个体中病毒粒子产生能力受损相关（P<0.05）。亚硫酸氢盐DNA测序显示，HBeAg阴性患者的甲基化密度显著高于HBeAg阳性患者（P<0.05）。HBeAg阴性患者中cccDNA的CpG岛2甲基化水平高于HBeAg阳性患者，提示乙肝病毒cccDNA甲基化可能与乙肝病毒复制能力有关。
