中国科学院昆明动物研究所机构知识库

高效抗逆转录疗法（HAART）的使用使得获得性免疫缺陷综合症（AIDS）从致死性疾病成为了能够靠医疗手段控制的慢性疾病。CCR5是HIV进入细胞所需的辅助受体之一，CCR5拮抗剂能够有效抑制R5嗜性病毒的复制。马拉维诺（MVC）是目前唯一获得FDA批准用于抗HIV临床治疗的CCR5拮抗剂。然而，耐药性的产生、对hERG及CYP450的抑制作用限制了MVC疗效。因此基于CCR5结构设计安全有效的CCR5拮抗剂具有重大意义。植物是发现各种先导化合物的重要来源。植物中能够分离提取得到多种佛波醇类化合物。这类化合物被发现具有很强的抗HIV活性，或能一定程度激活潜伏状态HIV的复制。典型的佛波醇酯化衍生物佛波酯PMA能够通过PKC途径刺激H9细胞中APOBEC3G（A3G）的表达。在非允许型细胞中，A3G能够被包裹进入新装配的病毒粒子中，在子代病毒感染细胞后的逆转录过程中，介导病毒DNA的G→A突变，从而抑制病毒复制。我们检测了125个CCR5拮抗剂对R5嗜性HIV-1实验株的抑制活性，发现15个化合物能在纳摩尔每升水平浓度抑制病毒的复制。从中选择具有良好生物利用度和安全性的DC521018，评价其在不同细胞中对HIV-1实验株、耐药株和临床分离株的抑制活性。DC521018结合于CCR5疏水口袋，与MVC的结合位点相同。研究发现，DC521018能够有效抑制R5嗜性HIV-1实验株和临床分离株，而对X4嗜性或R5X4嗜性的耐药病毒株无抑制效果，其活性与MVC接近。其细胞毒性比MVC小，且人血清对DC521018的屏蔽作用较弱。与多种不同类型抗HIV药物联合用药呈现协同或相加作用，而与MVC联合用药表现出拮抗作用，间接说明DC521018特异性地抑制CCR5。抗HIV临床前药效学评价结果显示，DC521018是一个低毒、高效的新型CCR5抑制剂，有望成为新的抗HIV候选药物，同时也为设计新的CCR5抑制剂提供了参考。从大戟科植物云南叶轮木的枝叶中分离提取得到的新型佛波酯12-O-Tricosanoyl-phorbol-20-acetate（hop-8），其结构最大特点是第12位羟基上连接了一条含23个碳原子的脂肪酰基侧链。抗HIV活性研究发现，hop-8是个广谱的HIV抑制剂，能够抑制多种HIV-1野生型和耐药性病毒株及HIV-2实验株在细胞内的复制，且细胞毒性低。其EC50范围为0.106 μM到7.987 μM。作用机制研究发现，hop-8能够上调非允许型细胞内A3G的表达，从而拮抗Vif介导的A3G降解，同时能够增加A3G在子代病毒粒子中的包装，抑制病毒复制。这项研究提示了一种潜在的治疗HIV感染新策略。

The nearly universally fatal desease, acquired immunodeficiency syndrome, or AIDS has been transformed to a medically managed condition since the highly active anti-retroviral therapy was used in patients who are live with HIV. CCR5 is one of the co-receptors in HIV entry and CCR5 antagonists could inhibit R5-tropism HIV infection effectively. Maraviroc is the only CCR5 antagonist that was approved to use for HIV treatment by U.S. FDA. However, the drug resistance and the inhibition of hERG and CYP450 limit the clinical use of MVC. Thus, designing novel CCR5 antagonists that are safe and effective is urgent as it is important.Plants are important resources for discovery of various lead compounds. Variety of phorbol esters were isolated and identified from plants. Various phorbol esters have been found to have strong anti-hiv activity, or can activate the latent HIV to a certain extent. The most commen phorbol ester is PMA which could upregulate APOBEC3G (A3G) expression in H9 cells through the PKC pathway. A3G is a member of the human cytidine deaminase family that restricts Vif-deficient viruses in nonpermissive cells by being packaged with progeny virions and inducing the G to A mutation during the synthesis of HIV-1 viral DNA when the progeny virus infects new cells.We screened the antiviral activity of 125 CCR5 antagonists against the R5-tropism HIV-1 lab-adapted strain, and found that 15 of them are highly efficient with EC50 at nanomole per liter level. Based on the bioavailability and safety, we choose DC521018 for further investigation. Through a collaboration with Dr. Liu’s group, we found that DC521018 binds deep into the binding pocket of CCR5, in a way similar to MVC by the X-ray crystal structure analyses. Consistant with this, DC521018 showed excellent antiviral activity against R5-tropism lab-adapted and clinical isolated HIV-1 strains in different cells. However, X4- or R5X4-tropism drug-resistant strains are not sensitive to DC521018, or MVC. Importantly, DC521018 has only slight reduction of antiviral activity caused by human serum, and it has lower cytotoxicity than MVC, making it an excellent drug candidate. DC521018 showed synergism or addition when combined with different classes of antiviral agent. The antagonism between MVC and DC521018 showed that DC521018 specifically inhibit CCR5. The preclinical antiviral activity show that DC521018 is a novel low-toxic CCR5 inhibitor, which is expected to be the new anti-hiv candidate drug, and also provides a reference for designing new CCR5 inhibitors.12-O-tricosanoylphorbol-20-acetate (hop-8), a novel phorbol ester that was isolated from the twigs and leaves of Ostodes katharinae of the family Euphorbiaceae, carried a tricosanoyl fatty acyl that never reported before. Hop-8 inhibited the replication of wild-type HIV-1 and HIV-2 strains and drug-resistant strains broadly in both C8166 cells and PBMCs with low cytotoxicity, with EC50 values ranging from 0.106 μM to 7.987 μM. One of the known mechanisms of hop-8 is to stimulate A3G expression in nonpermissive cells to counter the Vif-mediated A3G degradation and upregulation the A3G level in progeny virions, which results in reducing the infectivity of the progeny virus. This novel mechanism of hop-8 inhibition of HIV replication represents a potential approach for developing new therapeutics for HIV infection.