Meertens Laurent, Bertaux Claire, Dragic Tatjana
Department of Microbiology and Immunology, Albert Einstein College of Medicine, Jack & Pearl Resnick Campus, 1300 Morris Park Avenue, Golding B1, Bronx, NY 10461, USA.
J Virol. 2006 Dec;80(23):11571-8. doi: 10.1128/JVI.01717-06. Epub 2006 Sep 27.
Hepatitis C virus (HCV) is a major human pathogen associated with life-threatening liver disease. Entry into hepatocytes requires CD81 and a putative second receptor. In this study, we elucidated the postreceptor attachment stages of HCV entry using HCV pseudoparticles (HCVpp) as a model system. By means of dominant-negative mutants and short interfering RNAs of various cellular proteins, we showed that HCVpp enter via clathrin-coated vesicles and require delivery to early but not to late endosomes. However, the kinetics of HCV envelope glycoprotein-mediated fusion are delayed compared to those of other viruses that enter in early endosomes. Entry of HCVpp can be efficiently blocked by bafilomycin A1, which neutralizes the pH in early endosomes and impairs progression of endocytosis beyond this stage. However, low-pH exposure of bafilomycin A1-treated target cells does not induce entry of HCVpp at the plasma membrane or in the early stages of endocytosis. These observations indicate that, subsequent to internalization, HCVpp entry necessitates additional, low-pH-dependent interactions, modifications, or trafficking, and that these events are irreversibly disrupted by bafilomycin A1 treatment.
丙型肝炎病毒（HCV）是一种与危及生命的肝脏疾病相关的主要人类病原体。进入肝细胞需要CD81和一种假定的第二受体。在本研究中，我们以HCV假病毒颗粒（HCVpp）作为模型系统，阐明了HCV进入细胞的受体后附着阶段。通过各种细胞蛋白的显性负性突变体和小干扰RNA，我们发现HCVpp通过网格蛋白包被的小泡进入细胞，并且需要转运至早期内体而非晚期内体。然而，与那些进入早期内体的其他病毒相比，HCV包膜糖蛋白介导的融合动力学延迟。HCVpp的进入可被巴弗洛霉素A1有效阻断，巴弗洛霉素A1可中和早期内体的pH值，并损害内吞作用在此阶段之后的进展。然而，用巴弗洛霉素A1处理的靶细胞在低pH值暴露下并不会在质膜或内吞作用的早期阶段诱导HCVpp进入。这些观察结果表明，内化后，HCVpp的进入需要额外的、低pH值依赖性的相互作用、修饰或转运，并且这些事件会被巴弗洛霉素A1处理不可逆地破坏。
