Chronic hepatitis B virus (HBV) infection causes hepatitis, liver cirrhosis and hepatocellular carcinoma. Covalently closed circular DNA (cccDNA) is the sole viral transcription template and not affected by current treatment options, constituting a key determinant of HBV persistence. Novel therapeutics with demonstrable effectiveness against cccDNA are required. Methods: Previously, we established an HBV persistence mouse model using replicon plasmid derived from a clinical isolate (termed BPS) and identified IL-21 as a potent clearance-inducer. We also described another persistence mouse model based on cccDNA mimics produced in vivo termed recombinant cccDNA (rcccDNA). In this work, effectiveness of IL-21-based gene and cellular therapies was tested using these models. Results: In both models of HBV persistence, single injections with adeno-associated virus (AAV) expressing murine IL-21 highly efficiently induced clearance of both HBV markers from serum, and more importantly, BPS DNA and rcccDNA from mouse liver. Mechanistically, IL-21-induced clearance was associated with activation and liver infiltration of CD8+ T cells, and CD8 antibody injections negatively affected AAV-IL-21 effectiveness. More notably, adoptive transfer of CD8+ T cells from AAV-IL-21-cured mice engendered clearance in acceptor HBV persistence mice. Furthermore, cured mice were protected against re-challenge with long-lived memory. Most significantly, infusion of splenocytes from treatment-naïve mice stimulated ex vivo with IL-21 protein and HBV antigen could also induce clearance in treatment-naïve mice. Conclusion: These data demonstrate IL-21-based gene and cellular therapies as valid candidates for treating chronic HBV infections, with potential in removing cccDNA-harboring hepatocytes via activated CD8+ T cells accompanied by long-term protective memory.

中文翻译：

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基于IL-21的疗法可在小鼠模型中清除乙型肝炎病毒的持久性。

慢性乙型肝炎病毒（HBV）感染会导致肝炎，肝硬化和肝细胞癌。共价封闭的环状DNA（cccDNA）是唯一的病毒转录模板，不受当前治疗方案的影响，是决定HBV持久性的关键因素。需要具有针对cccDNA的可证明的有效性的新型治疗剂。方法：以前，我们使用源自临床分离株（称为BPS）的复制子质粒建立了HBV持久性小鼠模型，并将IL-21鉴定为有效的清除诱导剂。我们还描述了另一种基于体内产生的cccDNA模拟物的持久性小鼠模型，称为重组cccDNA（rcccDNA）。在这项工作中，使用这些模型测试了基于IL-21的基因和细胞疗法的有效性。结果：在两种HBV持续性模型中，单次注射表达鼠IL-21的腺相关病毒（AAV）可以有效地从血清中清除HBV标记，更重要的是从小鼠肝脏中清除BPS DNA和rcccDNA。从机理上讲，IL-21诱导的清除与CD8 + T细胞的活化和肝浸润有关，而CD8抗体注射对AAV-IL-21的效力产生负面影响。更值得注意的是，从AAV-IL-21治愈的小鼠中CD8 + T细胞的过继转移引起受体HBV持久性小鼠的清除。此外，可以保护治愈的小鼠免受长寿记忆的再次攻击。最重要的是，输注IL-21蛋白和HBV抗原离体刺激的未治疗小鼠的脾细胞也可诱导未治疗小鼠的清除。结论：