Abstract

Hepatitis B virus (HBV) infection is a major global health problem with over 240 million infected individuals at risk of developing progressive liver disease and hepatocellular carcinoma. HBV is an enveloped DNA virus that establishes its genome as an episomal, covalently closed circular DNA (cccDNA) in the nucleus of infected hepatocytes. Currently, available standard-of-care treatments for chronic hepatitis B (CHB) include nucleos(t)ide analogues (NAs) that suppress HBV replication but do not target the cccDNA and hence rarely cure infection. There is considerable interest in determining the lifespan of cccDNA molecules to design and evaluate new curative treatments. We took a novel approach to this problem by developing a new mathematical framework to model changes in evolutionary rates during infection which, combined with previously determined within-host evolutionary rates of HBV, we used to determine the lifespan of cccDNA. We estimate that during HBe-antigen positive (HBeAg^POS) infection the cccDNA lifespan is 61 (36–236) days, whereas during the HBeAg^NEG phase of infection it is only 26 (16–81) days. We found that cccDNA replicative capacity declined by an order of magnitude between HBeAg^POS and HBeAg^NEG phases of infection. Our estimated lifespan of cccDNA is too short to explain the long durations of chronic infection observed in patients on NA treatment, suggesting that either a sub-population of long-lived hepatocytes harbouring cccDNA molecules persists during therapy, or that NA therapy does not suppress all viral replication. These results provide a greater understanding of the biology of the cccDNA reservoir and can aid the development of new curative therapeutic strategies for treating CHB.

中文翻译：

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估计慢性感染中乙型肝炎病毒 cccDNA 的持久性†

 抽象的

乙型肝炎病毒 (HBV) 感染是一个主要的全球健康问题，超过 2.4 亿感染者面临发展为进行性肝病和肝细胞癌的风险。 HBV 是一种有包膜 DNA 病毒，其基因组在受感染肝细胞的细胞核中以附加型、共价闭合环状 DNA (cccDNA) 的形式建立。目前，慢性乙型肝炎 (CHB) 的可用标准治疗方法包括抑制 HBV 复制但不靶向 cccDNA 的核苷（酸）类似物 (NA)，因此很少能治愈感染。人们对确定 cccDNA 分子的寿命以设计和评估新的治疗方法非常感兴趣。我们采用了一种新颖的方法来解决这个问题，开发了一个新的数学框架来模拟感染期间进化速率的变化，结合之前确定的 HBV 宿主内进化速率，我们用来确定 cccDNA 的寿命。我们估计，在 HBe 抗原阳性 (HBeAg ^POS ) 感染期间，cccDNA 寿命为 61 (36–236) 天，而在 HBeAg ^NEG感染阶段仅为 26 (16–81) 天。我们发现，在 HBeAg ^POS和 HBeAg ^NEG感染阶段之间，cccDNA 复制能力下降了一个数量级。我们估计的 cccDNA 寿命太短，无法解释在接受 NA 治疗的患者中观察到的慢性感染持续时间长的现象，这表明，要么是含有 cccDNA 分子的长寿肝细胞亚群在治疗期间持续存在，要么是 NA 治疗并没有抑制所有病毒复制。 这些结果使人们对 cccDNA 储存库的生物学有了更深入的了解，并有助于开发治疗 CHB 的新治疗策略。