CD59在慢性丙型肝炎病毒感染中的作用

The mechanism of chronic HCV infection is very complicated.Probably the unbalance of complement is one of important molecule mechanism and regulators of complement activation(RCA) play very important roles in it.CD59 was first identified as a regulator of the terminal pathway of complement,which acts by binding to the C8/C9 components of the assembling membrane attack complex to inhit formation of lytic pore. Studies have shown clear evidence for its signalling properties.Several enveloped viruses such as HIV-1 virus have been found to incorporate host regulators of complement activation into their viral envelopes and, as a result, escape antibody-dependent omplement-mediated lysis (ADCML). HCV is an enveloped virus of the family Flaviviridae and incorporates more than 10 host lipoproteins. Patients chronically infected with HCV develop high-titer and cross-reactive neutralizing antibodies (nAbs) yet fail to clear the irus, raising the possibility that HCV may also use the similar strategy of RCA incorporation to escape ADCML. The current study will therefore be undertaken to determine whether HCV virions incorporate biologically functional CD59. Our experiments will aslo demonstrate that CD59 is associated with the external membrane of HCV particles derived from either Huh7.5.1 cells or plasma samples from HCV-infected patients. First, HCV particles are captured by CD59-specific Abs. Second, CD59 are detected in purified HCV particles by immunoblot analysis and in the cell-free supernatant from HCV-infected Huh7.5.1 cells, but not from uninfected Huh7.5.1 cells by ELISA. Then, abrogation of CD59 function with its blockers will increase the sensitivity of HCV virions to ADCML, resulting in a significant reduction of HCV infectivity. Additionally, direct addition of CD59 blockers into plasma samples from HCV-infected patients increased autologous virolysis. Finally,humoral and cellular immunity function also will be detected in our study.We will provide theoretical basis to make clear the mechanism of HCV chronic infection and explore specific antiviral drugs.

丙型肝炎慢性化机制十分复杂，其中补体作用失衡很可能是丙肝患者肝脏损伤的重要分子机制之一，而补体调节蛋白在补体作用失衡中又应起着极为重要的作用。GPI锚固的CD59是一重要的补体活化调节蛋白,通过阻止终末阶段攻膜复合物的形成,来防止补体活化造成对自身组织细胞的损伤。同时作为一重要的信号转导分子,CD59参与单核细胞、粒细胞、T细胞等活化信号转导过程。基于CD59在HIV-1等病毒感染中的研究，以及HCV感染及逃避免疫清除方面与HIV-1的相似性，本课题从是否HCV能够劫持CD59，并将其整合到病毒包膜上，从而逃避补体介导的溶解作用，使HCV感染持续存在；以及 HCV劫持CD59对机体细胞免疫及体液免疫如T细胞、B细胞、NK细胞功能所产生的影响进行研究，以深入探讨CD59参与HCV感染的分子机制。为进一步阐明HCV感染相关疾病的发病机制提供一定的理论依据，为抗HCV特异性药物的研究开辟新方向。

我们的研究及文献表明，HCV病毒RNA以膜相关的复制复合物形式进行复制，包括病毒结构蛋白、RNA复制、细胞膜的形成。新合成的病毒基因组进入内质网腔形成病毒颗粒，内质网对于病毒包膜形成及病毒成熟起到非常重要的作用，而对所有真核细胞中GPI-Aps如CD59的合成及调节也起着关键作用。因此，HCV也可能遇到并获得内质网及其他细胞器中的CD59或其他GPI-Aps，进而影响 HCV持续感染。结果表明HCV劫持CD59，还可影响细胞及体液免疫，导致HCV不能被有效清除。该研究为更好的治疗靶点药物提供理论依据。项目研究表明，IFNL4 ss154949590 TT/TT基因型利于HCV的自发清除。SLC4A11 rs3810560基因多态性可独立影响慢丙肝患者普通干扰素-α2b联合利巴韦林治疗预后；而SLC29A1 rs760370及 KLF12 rs9543524多态性则与治疗后出现的一系列不良反应有密切联系。本项目还从整体水平上比较了丙型肝炎自愈患者和慢性感染病人之间T细胞反应差异，发现相较于慢性感染患者，自愈患者具有更强的T细胞反应水平；筛选出的得分较高的多肽表位，将可成为设计HCV多肽疫苗的潜在T细胞表位。