Institute of Life Sciences, Bhubaneswar, Odisha, India.
Regional Centre for Biotechnology, Faridabad, Delhi, India.
J Virol. 2023 Jul 27;97(7):e0018023. doi: 10.1128/jvi.00180-23. Epub 2023 Jun 20.
Although most of the early events of the hepatitis C virus (HCV) life cycle are well characterized, our understanding of HCV egress is still unclear. Some reports implicate the conventional endoplasmic reticulum (ER)-Golgi route, while some propose noncanonical secretory routes. Initially, the envelopment of HCV nucleocapsid occurs by budding into the ER lumen. Subsequently, the HCV particle exit from the ER is assumed to be mediated by coat protein complex II (COPII) vesicles. COPII vesicle biogenesis also involves the recruitment of cargo to the site of vesicle biogenesis via interaction with COPII inner coat proteins. We investigated the modulation and the specific role of the individual components of the early secretory pathway in HCV egress. We observed that HCV inhibits cellular protein secretion and triggers the reorganization of the ER exit sites and ER-Golgi intermediate compartments (ERGIC). Gene-specific knockdown of the components of this pathway such as SEC16A, TFG, ERGIC-53, and COPII coat proteins demonstrated the functional significance of these components and the distinct role played by these proteins in various aspects of the HCV life cycle. SEC16A is essential for multiple steps in the HCV life cycle, whereas TFG is specifically involved in HCV egress and ERGIC-53 is crucial for HCV entry. Overall, our study establishes that the components of the early secretory pathway are essential for HCV propagation and emphasize the importance of the ER-Golgi secretory route in this process. Surprisingly, these components are also required for the early stages of the HCV life cycle due to their role in overall intracellular trafficking and homeostasis of the cellular endomembrane system. The virus life cycle involves entry into the host, replication of the genome, assembly of infectious progeny, and their subsequent release. Different aspects of the HCV life cycle, including entry, genome replication, and assembly, are well characterized; however, our understanding of the HCV release is still not clear and subject to debate due to varied findings. Here, we attempted to address this controversy and enhance our understanding of HCV egress by evaluating the role of the different components of the early secretory pathway in the HCV life cycle. To our surprise, we found that the components of the early secretory pathway are not only essential for HCV release but also contribute to many other earlier events of the HCV life cycle. This study emphasizes the importance of the early secretory pathway for the establishment of productive HCV infection in hepatocytes.
虽然丙型肝炎病毒 (HCV) 生命周期的早期事件大多已得到很好的描述，但我们对 HCV 出芽的理解仍不清楚。一些报告暗示了传统的内质网 (ER)-高尔基体途径，而另一些则提出了非规范的分泌途径。最初，HCV 核衣壳的包裹通过进入 ER 腔而发生。随后，假设 HCV 颗粒从 ER 中的逸出是由衣壳蛋白复合物 II (COPII) 小泡介导的。COPII 小泡的生物发生还涉及通过与 COPII 内衣蛋白相互作用将货物募集到小泡生物发生部位。我们研究了早期分泌途径的各个成分对 HCV 出芽的调节和特定作用。我们观察到 HCV 抑制细胞蛋白分泌，并触发 ER 出口部位和 ER-高尔基体中间隔室 (ERGIC) 的重排。该途径的成分（如 SEC16A、TFG、ERGIC-53 和 COPII 衣壳蛋白）的基因特异性敲低表明了这些成分的功能意义，以及这些蛋白质在 HCV 生命周期的各个方面所起的独特作用。SEC16A 对 HCV 生命周期的多个步骤是必不可少的，而 TFG 专门参与 HCV 出芽，ERGIC-53 对 HCV 进入至关重要。总体而言，我们的研究确立了早期分泌途径的成分对于 HCV 繁殖是必不可少的，并强调了 ER-Golgi 分泌途径在这一过程中的重要性。令人惊讶的是，由于它们在细胞内运输和细胞内膜系统的整体内稳态中的作用，这些成分对于 HCV 生命周期的早期阶段也是必需的。病毒生命周期包括进入宿主、基因组复制、组装感染性后代及其随后的释放。HCV 生命周期的不同方面，包括进入、基因组复制和组装，都得到了很好的描述；然而，由于发现的多样性，我们对 HCV 释放的理解仍然不清楚，并且存在争议。在这里，我们试图通过评估早期分泌途径的不同成分在 HCV 生命周期中的作用来解决这一争议，并增强我们对 HCV 出芽的理解。令我们惊讶的是，我们发现早期分泌途径的成分不仅对 HCV 释放是必不可少的，而且对 HCV 生命周期的许多其他早期事件也有贡献。这项研究强调了早期分泌途径对于建立有效的 HCV 感染在肝细胞中的重要性。
