Mechanism of action of interferon and ribavirin in treatment of hepatitis C

Since the identification of the hepatitis C virus, great strides have been made in the development of an antiviral therapy. As a crucial mediator of the innate antiviral immune response, interferon-alpha (IFN-alpha) was a natural choice for treatment. Whereas treatment with IFN-alpha alone achieved only modest success, the addition of the broad-spectrum antiviral agent ribavirin greatly improved responses. However, half of the infected individuals with chronic disease do not achieve sustained clearance of hepatitis C virus. To optimize current therapeutic strategies and to develop new therapies, a better understanding of the mechanism of action of IFN and ribavirin will be essential.     

Unscrambling hepatitis C virus-host interactions

The human suffering exacted by the hepatitis C virus is enormous. Hundreds of thousands of people die each year from liver failure and cancer caused by this infection. There is no vaccine, and the available antiviral drugs are toxic, expensive and only partly effective. Progress has been hindered by the absence of cell culture and small-animal models of the infection. Nonetheless, recent advances have yielded several promising new antiviral drugs and enhanced the prospects of developing a vaccine. The recent development of a robust in vitro hepatitis C virus infection system will aid this search.     

HBV基因型与干扰素及核苷类似物抗病毒治疗疗效的关系

目的:介绍乙型肝炎病毒(HBV)基因型与抗病毒治疗疗效关系的最新进展.方法:综合分析近年国内外有关HBV基因型与抗病毒治疗疗效关系的文献资料.结果:感染HBV基因型A的慢性乙型肝炎患者对干扰素治疗的应答率高于基因型D,基因型B高于基因型C;HBV基因型与核苷类似物治疗疗效的关系目前尚存争议;基因型E、F、G、H是否影响抗病毒疗效报道较少.结论:HBV基因型与抗病毒治疗疗效存在一定的相关性;HBV基因型的研究将有助于临床抗病毒治疗方案的优化.     

Interferon modulation of cellular microRNAs as an antiviral mechanism

RNA interference through non-coding microRNAs (miRNAs) represents a vital component of the innate antiviral immune response in plants and invertebrate animals; however, a role for cellular miRNAs in the defence against viral infection in mammalian organisms has thus far remained elusive. Here we show that interferon beta (IFNbeta) rapidly modulates the expression of numerous cellular miRNAs, and that eight of these IFNbeta-induced miRNAs have sequence-predicted targets within the hepatitis C virus (HCV) genomic RNA. The introduction of synthetic miRNA-mimics corresponding to these IFNbeta-induced miRNAs reproduces the antiviral effects of IFNbeta on HCV replication and infection, whereas neutralization of these antiviral miRNAs with anti-miRNAs reduces the antiviral effects of IFNbeta against HCV. In addition, we demonstrate that IFNbeta treatment leads to a significant reduction in the expression of the liver-specific miR-122, an miRNA that has been previously shown to be essential for HCV replication. Therefore, our findings strongly support the notion that mammalian organisms too, through the interferon system, use cellular miRNAs to combat viral infections.     

Unravelling hepatitis C virus replication from genome to function

Since the discovery of the hepatitis C virus over 15 years ago, scientists have raced to develop diagnostics, study the virus and find new therapies. Yet virtually every attempt to dissect this pathogen has met with roadblocks that impeded progress. Its replication was restricted to humans or experimentally infected chimpanzees, and efficient growth of the virus in cell culture failed until very recently. Nevertheless hard-fought progress has been made and the first wave of antiviral drugs is entering clinical trials.     

A diverse range of gene products are effectors of the type I interferon antiviral response

The type I interferon response protects cells against invading viral pathogens. The cellular factors that mediate this defence are the products of interferon-stimulated genes (ISGs). Although hundreds of ISGs have been identified since their discovery more than 25 years ago, only a few have been characterized with respect to antiviral activity. For most ISG products, little is known about their antiviral potential, their target specificity and their mechanisms of action. Using an overexpression screening approach, here we show that different viruses are targeted by unique sets of ISGs. We find that each viral species is susceptible to multiple antiviral genes, which together encompass a range of inhibitory activities. To conduct the screen, more than 380 human ISGs were tested for their ability to inhibit the replication of several important human and animal viruses, including hepatitis C virus, yellow fever virus, West Nile virus, chikungunya virus, Venezuelan equine encephalitis virus and human immunodeficiency virus type-1. Broadly acting effectors included IRF1, C6orf150 (also known as MB21D1), HPSE, RIG-I (also known as DDX58), MDA5 (also known as IFIH1) and IFITM3, whereas more targeted antiviral specificity was observed with DDX60, IFI44L, IFI6, IFITM2, MAP3K14, MOV10, NAMPT (also known as PBEF1), OASL, RTP4, TREX1 and UNC84B (also known as SUN2). Combined expression of pairs of ISGs showed additive antiviral effects similar to those of moderate type I interferon doses. Mechanistic studies uncovered a common theme of translational inhibition for numerous effectors. Several ISGs, including ADAR, FAM46C, LY6E and MCOLN2, enhanced the replication of certain viruses, highlighting another layer of complexity in the highly pleiotropic type I interferon system.     

RNA interference-mediated inhibition of Hepatitis B Virus replication

Persistent and recurrent infection of hepatitis B virus (HBV) represents one of the most common and severe viral infections of humans, and has caused a formidable health problem in the affected countries. Currently used antiviral drugs have a very limited success on controlling HBV replication and infection. RNA interference (RNAi), a process by which double-stranded RNA (dsRNA) directs sequence-specific degradation of target mRNA in mammalian and plant cells, has recently been used to knockdown gene expression in various species. In this study, we sought to determine whether RNAi-mediated silencing of HBV viral gene expression could lead to the effective inhibition of HBV replication. We first developed RNAi vectors that expressed small interfering RNA (siRNA) and targeted the HBV core or surface gene sequence. Our results demonstrated that these specific siRNAs efficiently reduced the levels of corresponding viral RNAs and proteins, and thus suppressed viral replication. Treatment with siRNA gave the greatest reduction in the levels of HBsAg (92%) and in HBeAg (85%) respectively in the cultured cell medium. Our findings further demonstrated that the RNAi-mediated antiviral effect was sequence-specific and dose-dependent. Therefore, our findings strongly suggest that RNAi-mediated silencing of HBV viral genes could effectively inhibit the replication of HBV, hence RNAi-based strategy should be further explored as a more efficacious antiviral therapy of HBV infection.     

慢性乙型肝炎临床治疗的现状与挑战

 病毒本身和机体免疫应答是影响HBV感染病情进展和临床转归的重要因素。目前免疫学研究及临床观察结果表明,单纯的抗病毒治疗无法重建慢性乙型肝炎患者的抗病毒免疫功能,因而无法彻底治愈HBV感染。联合新的免疫治疗策略,根据疾病的不同阶段采取针对性的治疗方案,可能是实现HBV感染治愈的有效方法。本文综述慢性乙型肝炎治疗的现状与进展。     

绿茶多酚表没食子儿茶素没食子酸酯（EGCG）体外对抗乙肝病毒复制的能力

研究目的：乙肝是尚未解决的公众健康问题,需要开发新型抗病毒药物。本研究拟从天然植物绿茶中寻找有效、经济、毒副作用低的抗乙肝病毒药物。创新要点：研究方法：重要结论首次以HepG22．2．15细胞为载体,发现EGCG对乙肝病毒HBsAg、HBeAg和HBVDNA的选择性作用。采用酶联免疫吸附实验（ELISA）检测细胞上清中HBsAg和HBeAg的含量,采用反转录聚合酶链反应（RT-PCR）检测上清和细胞内HBVDNA的含量。EGCG的浓度在0．11～0．44μmol／ml（即50～200μg／ml）的范围内能有效抑制HepG22．2．15细胞中HBsAg和HBeAg的分泌,其效果甚至优于浓度为0．87μmol／ml（即200μg/ml）的拉米夫定（3TC）,并且具有时间和剂量依赖性。同时,EGCG也能抑制胞外HBV DNA的表达。研究结果表明,EGCG具有良好抗病毒活性和低毒副作用,有望开发成为一种新的抗病毒药物。     

Small molecule inhibitors reveal Niemann-Pick C1 is essential for Ebola virus infection

Ebola virus (EboV) is a highly pathogenic enveloped virus that causes outbreaks of zoonotic infection in Africa. The clinical symptoms are manifestations of the massive production of pro-inflammatory cytokines in response to infection and in many outbreaks, mortality exceeds 75%. The unpredictable onset, ease of transmission, rapid progression of disease, high mortality and lack of effective vaccine or therapy have created a high level of public concern about EboV. Here we report the identification of a novel benzylpiperazine adamantane diamide-derived compound that inhibits EboV infection. Using mutant cell lines and informative derivatives of the lead compound, we show that the target of the inhibitor is the endosomal membrane protein Niemann-Pick C1 (NPC1). We find that NPC1 is essential for infection, that it binds to the virus glycoprotein (GP), and that antiviral compounds interfere with GP binding to NPC1. Combined with the results of previous studies of GP structure and function, our findings support a model of EboV infection in which cleavage of the GP1 subunit by endosomal cathepsin proteases removes heavily glycosylated domains to expose the amino-terminal domain, which is a ligand for NPC1 and regulates membrane fusion by the GP2 subunit. Thus, NPC1 is essential for EboV entry and a target for antiviral therapy.     

对丙型肝炎病毒具有潜在抑制作用的 L-苯丙氨酸衍生物前体的合成

丙型肝炎病毒（HCV ）感染与肝脏病变密切相关，是造成慢性肝炎、肝硬化及肝脏细胞肿瘤的主要原因之一．由于病毒自身的生物学特性，目前仍然没有有效的疫苗和治疗药物，研究开发高效的抗病毒药物具有重要意义．Reddy和他的小组设计合成了一系列 N，N-二取代的苯丙氨酸类似物，并证明了具有该种结构的化合物可对肝炎病毒聚合酶具有很好的抑制作用，以 L-苯丙氨酸为起始原料，经过酯化成氨基酸甲酯、与不同取代基的芳香醛缩合成希夫碱、将亚胺结构还原、酸化脱酯4步反应合成了8种对丙型肝炎病毒具有潜在抑制作用的此类化合物的前体，最高总产率达到77．4％．测定产物熔点，通过核磁氢谱对目标产物的结构进行表征，结果表明实现了目标化合物的合成．     

Natural killer cells act as rheostats modulating antiviral T cells

Antiviral T cells are thought to regulate whether hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections result in viral control, asymptomatic persistence or severe disease, although the reasons for these different outcomes remain unclear. Recent genetic evidence, however, has indicated a correlation between certain natural killer (NK)-cell receptors and progression of both HIV and HCV infection, implying that NK cells have a role in these T-cell-associated diseases. Although direct NK-cell-mediated lysis of virus-infected cells may contribute to antiviral defence during some virus infections--especially murine cytomegalovirus (MCMV) infections in mice and perhaps HIV in humans--NK cells have also been suspected of having immunoregulatory functions. For instance, NK cells may indirectly regulate T-cell responses by lysing MCMV-infected antigen-presenting cells. In contrast to MCMV, lymphocytic choriomeningitis virus (LCMV) infection in mice seems to be resistant to any direct antiviral effects of NK cells. Here we examine the roles of NK cells in regulating T-cell-dependent viral persistence and immunopathology in mice infected with LCMV, an established model for HIV and HCV infections in humans. We describe a three-way interaction, whereby activated NK cells cytolytically eliminate activated CD4 T cells that affect CD8 T-cell function and exhaustion. At high virus doses, NK cells prevented fatal pathology while enabling T-cell exhaustion and viral persistence, but at medium doses NK cells paradoxically facilitated lethal T-cell-mediated pathology. Thus, NK cells can act as rheostats, regulating CD4 T-cell-mediated support for the antiviral CD8 T cells that control viral pathogenesis and persistence.     

Murine cells expressing an HLA molecule are specifically lysed by HLA-restricted antiviral human T cells

Class I HLA (histocompatibility locus antigen) molecules are the targets of allospecific cytolytic T lymphocytes (CTL) in graft rejection, and constitute the restricting elements necessary for the interaction between antiviral CTL and virus-infected cells. Cells expressing only one HLA in the absence of other human molecules would provide a remarkable model for studying the function of these molecules. However, HLA+ murine cells transfected with human genes are generally not lysed by allospecific human CTL, and this is ascribed to insufficient HLA expression, lack of human beta 2-microglobulin, alteration of HLA molecules or absence of receptors for human T8 or LFA1 molecules in murine cells. Here we report, for the first time, the specific lysis of virus-infected HLA+ murine cells by HLA-restricted antiviral human CTL. Therefore, these murine cells constitute an excellent model for studying the role of HLA molecules.     

Structure of the catalytic domain of the hepatitis C virus NS2-3 protease

Hepatitis C virus is a major global health problem affecting an estimated 170 million people worldwide. Chronic infection is common and can lead to cirrhosis and liver cancer. There is no vaccine available and current therapies have met with limited success. The viral RNA genome encodes a polyprotein that includes two proteases essential for virus replication. The NS2-3 protease mediates a single cleavage at the NS2/NS3 junction, whereas the NS3-4A protease cleaves at four downstream sites in the polyprotein. NS3-4A is characterized as a serine protease with a chymotrypsin-like fold, but the enzymatic mechanism of the NS2-3 protease remains unresolved. Here we report the crystal structure of the catalytic domain of the NS2-3 protease at 2.3 A resolution. The structure reveals a dimeric cysteine protease with two composite active sites. For each active site, the catalytic histidine and glutamate residues are contributed by one monomer, and the nucleophilic cysteine by the other. The carboxy-terminal residues remain coordinated in the two active sites, predicting an inactive post-cleavage form. Proteolysis through formation of a composite active site occurs in the context of the viral polyprotein expressed in mammalian cells. These features offer unexpected insights into polyprotein processing by hepatitis C virus and new opportunities for antiviral drug design.     

178例病毒性角膜炎伴发色素膜炎治疗分析

目的：探讨病毒性角膜炎伴发色素膜炎的临床特点、发病机理与治疗方法。方法：对178例患者的临床资料进行分析。结果：126例盘状角膜基质炎伴发色素膜炎的患者,临床治愈123例（治愈率97.6%）;随访1～5年,复发43例（复发率34.1%）。52例角膜内皮炎伴发色素膜炎的患者,临床治愈50例（治愈率96.1%）;随访1～5年,复发17例（复发率32.7%）。结论：病毒是引起角膜基质炎及角膜内皮炎主要病原,而只有在复发时免疫成分才具有重要性。盘状角膜基质炎伴发色素膜炎治疗原则是加强抗病毒治疗,再适当联合糖皮质激素治疗：角膜内皮炎伴发色素膜炎治疗原则是加强糖皮质激素和免疫抑制剂（环孢霉素A）联合应用,再适当应用抗病毒药物治疗。伴发青光眼的患者以抗炎治疗为主,同时加用降眼压的药物。     

金丝桃素研究新进展

综述近几年国内外在金丝桃素含量及测定方法、提取、药理作用及临床应用等方面的最新研究成果，主要在金丝桃素的抗抑郁、抗病毒、治疗肝炎、治疗白血病、抗癌抗肿瘤等药理作用及临床应用方面作了系统的阐述，在此基础上讨论了金丝桃素需要进一步研究的问题，为金丝桃素的近一步开发提供了文献依据．     

Antiviral treatment is more effective than smallpox vaccination upon lethal monkeypox virus infection

There is concern that variola virus, the aetiological agent of smallpox, may be used as a biological weapon. For this reason several countries are now stockpiling (vaccinia virus-based) smallpox vaccine. Although the preventive use of smallpox vaccination has been well documented, little is known about its efficacy when used after exposure to the virus. Here we compare the effectiveness of (1) post-exposure smallpox vaccination and (2) antiviral treatment with either cidofovir (also called HPMPC or Vistide) or with a related acyclic nucleoside phosphonate analogue (HPMPO-DAPy) after lethal intratracheal infection of cynomolgus monkeys (Macaca fascicularis) with monkeypox virus (MPXV). MPXV causes a disease similar to human smallpox and this animal model can be used to measure differences in the protective efficacies of classical and new-generation candidate smallpox vaccines. We show that initiation of antiviral treatment 24 h after lethal intratracheal MPXV infection, using either of the antiviral agents and applying various systemic treatment regimens, resulted in significantly reduced mortality and reduced numbers of cutaneous monkeypox lesions. In contrast, when monkeys were vaccinated 24 h after MPXV infection, using a standard human dose of a currently recommended smallpox vaccine (Elstree-RIVM), no significant reduction in mortality was observed. When antiviral therapy was terminated 13 days after infection, all surviving animals had virus-specific serum antibodies and antiviral T lymphocytes. These data show that adequate preparedness for a biological threat involving smallpox should include the possibility of treating exposed individuals with antiviral compounds such as cidofovir or other selective anti-poxvirus drugs.     

Modelling how ribavirin improves interferon response rates in hepatitis C virus infection

Nearly 200 million individuals worldwide are currently infected with hepatitis C virus (HCV). Combination therapy with pegylated interferon and ribavirin, the latest treatment for HCV infection, elicits long-term responses in only about 50% of patients treated. No effective alternative treatments exist for non-responders. Consequently, significant efforts are continuing to maximize response to combination therapy. However, rational therapy optimization is precluded by the poor understanding of the mechanism(s) of ribavirin action against HCV. Ribavirin alone induces either a transient early decline or no decrease in HCV viral load, but in combination with interferon it significantly improves long-term response rates. Here we present a model of HCV dynamics in which, on the basis of growing evidence, we assume that ribavirin decreases HCV infectivity in an infected individual in a dose-dependent manner. The model quantitatively predicts long-term response rates to interferon monotherapy and combination therapy, fits observed patterns of HCV RNA decline in patients undergoing therapy, reconciles conflicting observations of the influence of ribavirin on HCV RNA decline, provides key insights into the mechanism of ribavirin action against HCV, and establishes a framework for rational therapy optimization.     

带状疱疹神经阻滞的对比性观察

将90例带状疱疹患者分为三组：A组为头面部及上肢患者组,采用行星状神经节阻滞;B组为胸腹部患者组,采用硬膜外隙注药;C组病变部位与B组相同,采用皮肤科常规综合治疗。结果表明：接受星状神经节阻滞和硬膜外给药,A,B组止痛优良率分别为90％和93．3％;C组优良率仅为40％。A,B组平均病程为12．4d和11．8d,C组平均病程为17．2d。A,B组与C组相比较,差异具有统计学显著性（P＜0．05）。结果表明：星状神经节阻滞和硬膜外隙注药比皮肤科综合治疗止痛效果好,且具有使患者缩短病程、康复快的临床效果。