Department of Gastroenterology and Hepatology, Nagoya University Graduate School of Medicine, Nagoya.
Department of Virology II, National Institute of Infectious Diseases, Tokyo.
Cell Mol Gastroenterol Hepatol. 2021;12(5):1583-1598. doi: 10.1016/j.jcmgh.2021.07.013. Epub 2021 Aug 2.
BACKGROUND & AIMS: To provide an adequate treatment strategy for chronic hepatitis B, it is essential to know which patients are expected to have a good prognosis and which patients do not require therapeutic intervention. Previously, we identified the substitution of isoleucine to leucine at amino acid 97 (I97L) in the hepatitis B core region as a key predictor among patients with stable hepatitis. In this study, we attempted to identify the point at which I97L affects the hepatitis B virus (HBV) life cycle and to elucidate the underlying mechanisms governing the stabilization of hepatitis.
To confirm the clinical features of I97L, we used a cohort of hepatitis B e antigen-negative patients with chronic hepatitis B infected with HBV-I97 wild-type (wt) or HBV-I97L. The effects of I97L on viral characteristics were evaluated by in vitro HBV production and infection systems with the HBV reporter virus and cell culture-generated HBV.
The ratios of reduction in hepatitis B surface antigen and HBV DNA were higher in patients with HBV-I97L than in those with HBV-I97wt. HBV-I97L exhibited lower infectivity than HBV-I97wt in both infection systems with reporter HBV and cell culture-generated HBV. HBV-I97L virions exhibiting low infectivity primarily contained a single-stranded HBV genome. The lower efficiency of cccDNA synthesis was demonstrated after infection of HBV-I97L or transfection of the molecular clone of HBV-I97L.
The I97L substitution reduces the level of cccDNA through the generation of immature virions with single-stranded genomes. This I97L-associated low efficiency of cccDNA synthesis may be involved in the stabilization of hepatitis.
为了提供慢性乙型肝炎的充分治疗策略，了解哪些患者具有良好的预后以及哪些患者不需要治疗干预至关重要。以前，我们发现乙型肝炎核心区第 97 位氨基酸（I97L）亮氨酸取代异亮氨酸是稳定型肝炎患者的关键预测指标。在这项研究中，我们试图确定 I97L 影响乙型肝炎病毒（HBV）生命周期的关键点，并阐明控制肝炎稳定的潜在机制。
为了确认 I97L 的临床特征，我们使用了一组乙型肝炎 e 抗原阴性的慢性乙型肝炎患者，这些患者感染了 HBV-I97 野生型（wt）或 HBV-I97L。通过使用 HBV 报告病毒和细胞培养生成的 HBV 的体外 HBV 产生和感染系统评估 I97L 对病毒特征的影响。
与 HBV-I97wt 相比，HBV-I97L 患者的乙型肝炎表面抗原和 HBV DNA 降低比例更高。在报告病毒和细胞培养生成的 HBV 的两种感染系统中，HBV-I97L 的感染性均低于 HBV-I97wt。表现出低感染性的 HBV-I97L 病毒颗粒主要含有单链 HBV 基因组。在感染 HBV-I97L 或转染 HBV-I97L 分子克隆后，cccDNA 合成的效率降低。
I97L 取代通过产生具有单链基因组的不成熟病毒颗粒降低了 cccDNA 的水平。这种与 I97L 相关的低 cccDNA 合成效率可能与肝炎的稳定有关。
