丙型肝炎病毒抗体依赖性增强作用的研究现状及意义

抗体协助病毒进入靶细胞，提高感染率，这一现象称为抗体依赖性增强作用（ADE）。ADE一方面保护免疫的诱导作用，另一方面增强敏感性的诱导作用，它们之间存在微妙的平衡关系。人们发现在多种病毒感染中广泛存在ADE效应，且常规疫苗预防及治疗此类病毒感染难以奏效。因此，近年来ADE越来越受到人们的重视。本文着重阐述ADE效应在丙型肝炎病毒（HCV）中的作用机制，旨为HCV发病机理及慢性丙型肝炎治疗、HCV疫苗研发提供新思路。     

寨卡病毒与登革热病毒交叉反应抗体引发严重性疾病的关系

登革病毒(DENV)不同血清型感染后,易导致抗体依赖增强反应(ADE)的严重性疾病发生。2015年5月巴西流行寨卡病毒(ZIKV)后,截止至2016年11月,流行已扩散到60多个国家和地区,毗邻我国的一些东南亚国家也有报告ZIKV感染病例。近期有研究显示,ZIKV和DENV的包膜(E)蛋白EDI和EDII两表位引发的抗体或由此产生的单克隆抗体具有很强的交叉反应性,易引起ADE的发生。我国沿海省份历年时有DENV病毒流行,今后ZIKV流行事件极有可能发生,因此,由该病毒流行引起的严重性疾病发生我们必须要关注和提出应对措施。     

寨卡病毒动物感染模型研究进展

寨卡病毒是一种经由蚊媒传播的重要的黄病毒属病毒,已导致全球数百万人感染,引发严峻的公共卫生危机。2015年以来,尤其是中南美洲地区暴发的寨卡疫情出现了新生儿小头畸形、大脑发育异常与格林巴列综合征等不同以往的严重症状,引发高度关注。合适的动物感染模型对于研究寨卡病毒的传播方式、致病机理及研发防控寨卡病毒感染的新药、疫苗及诊断试剂等都有十分重要的意义。本文就近年来建立的寨卡病毒动物感染模型进展进行综述。     

Ⅲ型干扰素抵抗寨卡病毒感染导致不良妊娠的机制

寨卡病毒是一种蚊媒黄病毒,妊娠早期妇女感染寨卡病毒可引起新生儿小头畸形、胎儿宫内发育迟缓及胎儿自发性流产等不良妊娠。人胎盘原代滋养细胞分泌的Ⅲ型干扰素及Ⅲ型干扰素诱导产生的干扰素刺激基因可在细胞中建立抗病毒状态,保护胎儿免受寨卡病毒的感染。Ⅲ型干扰素对寨卡病毒导致的不良妊娠保护作用具有阶段特异性,对妊娠早期没有保护作用。本文就寨卡病毒导致不良妊娠和Ⅲ型干扰素抵抗寨卡病毒感染等方面的机制研究进行综述,为深入了解寨卡病毒致病机制和免疫预防提供参考。     

Ⅲ型干扰素抵抗寨卡病毒感染导致不良妊娠的机制

寨卡病毒是一种蚊媒黄病毒,妊娠早期妇女感染寨卡病毒可引起新生儿小头畸形、胎儿宫内发育迟缓及胎儿自发性流产等不良妊娠。人胎盘原代滋养细胞分泌的Ⅲ型干扰素及Ⅲ型干扰素诱导产生的干扰素刺激基因可在细胞中建立抗病毒状态,保护胎儿免受寨卡病毒的感染。Ⅲ型干扰素对寨卡病毒导致的不良妊娠保护作用具有阶段特异性,对妊娠早期没有保护作用。本文就寨卡病毒导致不良妊娠和Ⅲ型干扰素抵抗寨卡病毒感染等方面的机制研究进行综述,为深入了解寨卡病毒致病机制和免疫预防提供参考。     

抗体同型应答与血吸虫感染后宿主获得性免疫力表达

自80年代以来，在抗血吸虫感染疫苗研究中有关抗体同型应答（Antibodyisotyperesponse）与血吸虫感染后宿主获得性免疫力表达的相关性研究受到了重视。现将有关材料综述如下。1血吸虫感染后获得性免疫机制与抗体同型应答动物实验证明，满主对血吸虫免疫效应机制可分为两类，第一类为抗体依赖的细胞介导的细胞毒反应（ADCC），包括IgE或IgG2：抗体、巨噬细胞、嗜酸性细胞和血小板。主要作用于在虫体表面有抗原表达的幼龄童虫［‘－’j。该动物模型为大鼠一曼氏血吸虫病的模型。第二类为小鼠一曼氏血吸虫病模型。观察到非抗体依赖的，以激…     

寨卡病毒病

寨卡病毒病是由寨卡病毒引起的急性传染病.人体因受携带病毒的雌性伊蚊叮咬而得病,为自限性疾病,隐性感染率高,症状轻,但有可能引起胎儿/婴儿小头畸形和格林-巴利综合征等严重并发症.实验室检测方法包括PCR检测病毒RNA和检测血清中的病毒抗体(IgM).该疾病目前无有效的抗病毒药物和疫苗,一般采用对症治疗的方法即可痊愈.寨卡病毒病的预防措施与其他虫媒病毒相同,即预防蚊虫叮咬和采取虫媒控制措施.该病上世纪中叶起源于非洲,2007年起传播范围不断扩大,速度不断加快.截止2015年3月,全球共有52个国家和地区有寨卡病毒本地传播.     

寨卡病毒病研究进展

寨卡病毒病是由寨卡病毒引起的一种自限性急性传染病。寨卡病毒主要通过埃及伊蚊和白纹伊蚊叮咬传播,有证据表明也可通过性传播和母婴传播。临床表现主要为皮疹、发热、关节痛或结膜炎等非特异性症状,但寨卡病毒感染与新生儿小头畸形、格林-巴利综合征等存在密切关系。实验室检测方法包括实时荧光定量PCR检测病毒核酸和ELISA检测Ig M抗体。该疾病目前无有效的抗病毒药物和疫苗。预防措施主要为预防蚊虫叮咬和采取虫媒控制措施。     

抗寨卡病毒非结构蛋白1单克隆抗体的制备与鉴定

目的制备抗寨卡病毒非结构蛋白1的小鼠杂交瘤单克隆抗体,并对筛选获得的单抗进行抗体亚型鉴定以及免疫结合特性鉴定。方法将真核表达纯化获得的寨卡病毒非结构蛋白1按50μg/只的量免疫3只SPF级BABL/c小鼠,经过3次皮下多点免疫及1次腹腔加强免疫后测定小鼠血清抗体效价,取抗体滴度高的免疫小鼠脾细胞与小鼠骨髓瘤细胞SP2/0进行细胞融合,使用有限稀释法进行亚克隆,采用间接ELISA筛选分泌高滴度单抗的杂交瘤细胞株,使用小鼠单克隆抗体分型试剂盒对筛选的单抗进行亚型鉴定,分别使用免疫印迹与间接免疫荧光法检测单抗与寨卡病毒非结构蛋白1以及寨卡病毒的免疫结合特性。结果寨卡病毒非结构蛋白1免疫刺激小鼠产生高滴度的抗体,ELISA滴度为1∶64000。通过筛选获得2株能高效分泌抗寨卡病毒非结构蛋白1单抗的杂交瘤细胞株(命名为1C9-F12,4B2-F3),分泌的单抗的亚型均为重链γ1和轻链Kappa;Western blot及IFA法检测2株单抗均能与寨卡病毒非结构蛋白1及寨卡病毒发生特异性结合。结论成功筛选到2个抗寨卡病毒非结构蛋白1的小鼠单克隆抗体,该两个单抗均具有寨卡病毒非结构蛋白1及寨卡病毒结合特性,为建立检测寨卡病毒感染的ELISA方法及治疗性抗体研究奠定了基础。     

体外感染实验探讨丙型肝炎病毒的ADE分子机制

目的研究丙型肝炎病毒(HCV)在感染人滋养层细胞的过程中是否存在抗体依赖性感染增强(ADE)作用,以探讨HCV母婴传播的分子机制。方法将HCV阳性血清以4种不同方式感染人滋养层细胞,以免疫电镜观察HCV病毒颗粒在滋养层细胞中的表达,应用RT-PCR法、免疫组化法检测细胞内外的HCVRNA正链、负链,HCVNS5、NS3及C区抗原。结果在滋养层细胞胞浆内发现了HCV病毒颗粒,HCVRNA正链、负链,HCVNS5、NS3、C区抗原仅在全血清感染细胞内或上清中间断测得。结论HCV可以在滋养层细胞中复制。HCV感染滋养层细胞的过程中存在ADE机制,抗体和补体均参与了HCV的跨膜转运过程。     

A Glimmer of Hope: Recent Updates and Future Challenges in Zika Vaccine Development

The emergence and rapid spread of Zika virus (ZIKV) on a global scale as well as the establishment of a causal link between Zika infection and congenital syndrome and neurological disorders triggered unprecedented efforts towards the development of a safe and effective Zika vaccine. Multiple vaccine platforms, including purified inactivated virus, nucleic acid vaccines, live-attenuated vaccines, and viral-vectored vaccines, have advanced to human clinical trials. In this review, we discuss the recent advances in the field of Zika vaccine development and the challenges for future clinical efficacy trials. We provide a brief overview on Zika vaccine platforms in the pipeline before summarizing the vaccine candidates in clinical trials, with a focus on recent, promising results from vaccine candidates that completed phase I trials. Despite low levels of transmission during recent years, ZIKV has become endemic in the Americas and the potential of large Zika outbreaks remains real. It is important for vaccine developers to continue developing their Zika vaccines, so that a potential vaccine is ready for deployment and clinical efficacy trials when the next ZIKV outbreak occurs.     

Zika virus from a Southeast Asian perspective

Phylogenic evidence suggests that the strain of Zika virus causing an unprecedented outbreak of disease in the Americas had its origin in Southeast Asia,where reports of isolated cases of Zika virus infection have occurred since 2010,Why there has been no large outbreak of Zika infection in Southeast Asia remains unclear and whether such an outbreak will occur in the future is a question of significant concern,This review looks at Zika virus from a Southeast Asian perspective and highlights some of the possible scenarios with regards to Zika virus in this part of the world as well as highlighting some of the research questions that need to be urgently addressed.     

Tree Shrew as an Emerging Small Animal Model for Human Viral Infection: A Recent Overview

Viral infection is a global public health threat causing millions of deaths. A suitable small animal model is essential for viral pathogenesis and host response studies that could be used in antiviral and vaccine development. The tree shrew (Tupaia belangeri or Tupaia belangeri chinenesis), a squirrel-like non-primate small mammal in the Tupaiidae family, has been reported to be susceptible to important human viral pathogens, including hepatitis viruses (e.g., HBV, HCV), respiratory viruses (influenza viruses, SARS-CoV-2, human adenovirus B), arboviruses (Zika virus and dengue virus), and other viruses (e.g., herpes simplex virus, etc.). The pathogenesis of these viruses is not fully understood due to the lack of an economically feasible suitable small animal model mimicking natural infection of human diseases. The tree shrew model significantly contributes towards a better understanding of the infection and pathogenesis of these important human pathogens, highlighting its potential to be used as a viable viral infection model of human viruses. Therefore, in this review, we summarize updates regarding human viral infection in the tree shrew model, which highlights the potential of the tree shrew to be utilized for human viral infection and pathogenesis studies.     

Studies of antibody-dependent enhancement of human immunodeficiency virus (HIV) type 1 infection mediated by Fc receptors using sera from recipients of a recombinant gp160 experimental HIV-1 vaccine.

Subneutralizing concentrations of sera from human immunodeficiency virus (HIV)-1-infected patients augment HIV infection mediated by Fc receptor uptake by human monocytes and the monocytic cell line U937. Antibody-dependent enhancement (ADE) and neutralization activity were studied in the sera of HIV-1 antibody-negative volunteers who had been immunized with three 40-micrograms doses of a recombinant gp160 (rgp160) candidate HIV vaccine. Volunteers were vaccinated with rgp160 or a hepatitis B vaccine as a control on days 0, 30, and 180. Sera were obtained before and after three doses of vaccine and were tested for ADE and neutralization activity. Serum samples collected before vaccination showed neither neutralization nor ADE activity. Thirteen sera from volunteers who received gp160 and four from placebo recipients failed to show ADE. Three sera showed low levels of neutralization of strain IIIB of HIV. Vaccination with this dose of rgp160 produced neutralizing antibodies in some subjects but did not induce detectable enhancing antibodies.     

Neutralizing antibody response to hepatitis C virus

A critical first step in a "rational vaccine design" approach for hepatitis C virus (HCV) is to identify the most relevant mechanisms of immune protection. Emerging evidence provides support for a protective role of virus neutralizing antibodies, and the ability of the B cell response to modify the course of acute HCV infection. This has been made possible by the development of in vitro cell culture models, based on HCV retroviral pseudotype particles expressing E1E2 and infectious cell culture-derived HCV virions, and small animal models that are robust tools in studies of antibody-mediated virus neutralization. This review is focused on the immunogenic determinants on the E2 glycoprotein mediating virus neutralization and the pathways in which the virus is able to escape from immune containment. Encouraging findings from recent studies provide support for the existence of broadly neutralization antibodies that are not associated with virus escape. The identification of conserved epitopes mediating virus neutralization that are not associated with virus escape will facilitate the design of a vaccine immunogen capable of eliciting broadly neutralizing antibodies against this highly diverse virus.     

The human antibody response to dengue virus infection

Dengue viruses (DENV) are the causative agents of dengue fever (DF) and dengue hemorrhagic fever (DHF). Here we review the current state of knowledge about the human antibody response to dengue and identify important knowledge gaps. A large body of work has demonstrated that antibodies can neutralize or enhance DENV infection. Investigators have mainly used mouse monoclonal antibodies (MAbs) to study interactions between DENV and antibodies. These studies indicate that antibody neutralization of DENVs is a "multi-hit" phenomenon that requires the binding of multiple antibodies to neutralize a virion. The most potently neutralizing mouse MAbs bind to surface exposed epitopes on domain III of the dengue envelope (E) protein. One challenge facing the dengue field now is to extend these studies with mouse MAbs to better understand the human antibody response. The human antibody response is complex as it involves a polyclonal response to primary and secondary infections with 4 different DENV serotypes. Here we review studies conducted with immune sera and MAbs isolated from people exposed to dengue infections. Most dengue-specific antibodies in human immune sera are weakly neutralizing and bind to multiple DENV serotypes. The human antibodies that potently and type specifically neutralize DENV represent a small fraction of the total DENV-specific antibody response. Moreover, these neutralizing antibodies appear to bind to novel epitopes including complex, quaternary epitopes that are only preserved on the intact virion. These studies establish that human and mouse antibodies recognize distinct epitopes on the dengue virion. The leading theory proposed to explain the increased risk of severe disease in secondary cases is antibody dependent enhancement (ADE), which postulates that weakly neutralizing antibodies from the first infection bind to the second serotype and enhance infection of FcγR bearing myeloid cells such as monocytes and macrophages. Here we review results from human, animal and cell culture studies relevant to the ADE hypothesis. By understanding how human antibodies neutralize or enhance DENV, it will be possible to better evaluate existing vaccines and develop the next generation of novel vaccines.     

Comparison of P388D1 mouse macrophage cell line and human monocytes for assay of dengue-2 infection-enhancing antibodies

Tissue culture-adapted dengue 2 virus (DEN 2), strain 16681, exhibits antibody-dependent enhancement of infection (ADE) in P388D1 cells, a mouse macrophage-like cell line. ADE is dependent upon maintaining DEN 2 multiplicity of infection at between 0.1 and 0.001, and can be simply measured in multi-well plastic plates. The assay uses either trypsinized or non-trypsinized P388D1 cells at 5 x 10(5) cells per ml, an appropriate dilution of DEN 2 virus, and a source of antibody, and is most conveniently performed without further washing of stationary cultures, which are incubated in 5% CO2. Trypsinization of P388D1 cells prior to the addition of virus-serum mixtures reduced infection in control cultures thus increasing ADE. When cells were washed after incubation of virus-serum mixtures for 1 hour, a paradoxical increase of infection in cultures exposed to virus plus normal serum was noted, which reduced the sensitivity of the ADE assay. Using human cord blood sera, ADE titers measured in human monocytes and P388D1 cells were closely similar. This convenient and economical assay will facilitate large scale biological and epidemiological studies of dengue virus enhancing antibodies.     

Use of Animal Models in Studying Roles of Antibodies and Their Secretion Cells in Dengue Vaccine Development

The cardinal feature of adaptive immunity is its ability to form memory responses that can be rapidly recalled to contain pathogens upon reencountering. Conferring a robust memory immune response to an infection is a key feature for a successful vaccination program. The plasmablasts are cells that not only can secret non-neutralizing antibodies but also can secrete the specific antibodies essential to neutralize and inactivate the invading pathogens. Dengue has been recognized as one of the most important vector-borne human viral diseases globally. Currently, supportive care with vigilant monitoring is the standard practice since there is as yet no approved therapeutic modality to treat dengue. Even though the approved vaccine has become available, its low efficacy with the potential to cause harm is the major hurdle to promote the widespread usage of the vaccine. Despite the decades of research on dengue, the major challenge in dengue vaccine development is the absence of suitable experimental animal models that reflect the pathological features and clinical symptoms, as seen in humans. Dengue is transmitted by the bite of mosquitoes carrying infectious dengue virus (DENV), which has four distinct serotypes. Recently, cases resulting from unconventional transmission routes, such as blood transfusion, organs as well as stem cells and bone marrow transplantations, and mother-to-infant vertical transmission, have been reported, suggesting an alternate route of DENV transmission exists in nature. This review discusses issues and challenges needing to be resolved to develop an effective dengue vaccine. Development of a robust and reliable dengue animal model that can reflect not only dynamic human clinical symptoms but also can answer around why preexisting neutralizing antibodies do not confer protection upon re-infection and immune protection marker for dengue vaccine efficacy evaluation.