Choline is an essential nutrient required for normal neuronal and muscular development, as well as homeostatic regulation of hepatic metabolism. In the liver, choline is incorporated into the main eukaryotic phospholipid, phosphatidylcholine (PC), and can enter one-carbon metabolism via mitochondrial oxidation. Hepatitis C virus (HCV) is a hepatotropic positive-strand RNA virus that similar to other positive-strand RNA viruses and can impact phospholipid metabolism. In the current study we sought to interrogate if HCV modulates markers of choline metabolism following in vitro infection, while subsequently assessing if the inhibition of choline uptake and metabolism upon concurrent HCV infection alters viral replication and infectivity. Additionally, we assessed whether these parameters were consistent between cells cultured in fetal bovine serum (FBS) or human serum (HS), conditions known to differentially affect in vitro HCV infection. We observed that choline transport in FBS- and HS-cultured Huh7.5 cells is facilitated by the intermediate affinity transporter, choline transporter-like family (CTL). HCV infection in FBS, but not HS-cultured cells diminished CTL1 transcript and protein expression at 24 h post-infection, which was associated with lower choline uptake and lower incorporation of choline into PC. No changes in other transporters were observed and at 96 h post-infection, all differences were normalized. Reciprocally, limiting the availability of choline for PC synthesis by use of a choline uptake inhibitor resulted in increased HCV replication at this early stage (24 h post-infection) in both FBS- and HS-cultured cells. Finally, in chronic infection (96 h post-infection), inhibiting choline uptake and metabolism significantly impaired the production of infectious virions. These results suggest that in addition to a known role of choline kinase, the transport of choline, potentially via CTL1, might also represent an important and regulated process during HCV infection.

中文翻译：

---

体外丙型肝炎病毒感染和肝胆碱代谢。

胆碱是正常神经元和肌肉发育以及肝代谢稳态调节所需的必需营养素。在肝脏中，胆碱被整合到主要的真核磷脂磷脂酰胆碱（PC）中，并可以通过线粒体氧化进入一碳代谢。丙型肝炎病毒（HCV）是一种与其他正链RNA病毒相似的促肝正链RNA病毒，可影响磷脂代谢。在当前的研究中，我们试图询问HCV是否在体外感染后调节胆碱代谢的标志物，同时随后评估在并发HCV感染后抑制胆碱摄取和代谢是否会改变病毒复制和感染性。另外，我们评估了这些参数在胎牛血清（FBS）或人血清（HS）中培养的细胞之间是否一致，已知这些条件会差异性影响体外HCV感染。我们观察到FBS和HS培养的Huh7.5细胞中的胆碱转运是由中间亲和力转运蛋白，胆碱转运蛋白样家族（CTL）促进的。FBS感染HCV，但HS培养细胞未感染HCV，从而在感染后24小时减少了CTL1转录和蛋白质表达，这与胆碱摄取降低和胆碱掺入PC的可能性降低有关。没有观察到其他转运蛋白的变化，并且在感染后96小时，所有差异均被标准化。相反，通过使用胆碱摄取抑制剂限制胆碱用于PC合成的可用性，导致在FBS和HS培养细胞的早期（感染后24小时）HCV复制增加。最后，在慢性感染中（感染后96小时），抑制胆碱的摄取和代谢会大大损害感染性病毒粒子的产生。这些结果表明，除了胆碱激酶的已知作用外，可能通过CTL1转运胆碱也可能代表HCV感染过程中重要且受调控的过程。