C-terminal lysosome targeting domain of CD63 modifies cellular localization of rabies virus glycoprotein

The glycoprotein of rabies virus is the central antigen elicited the immune response to infection; therefore, the majority of developing anti-rabies vaccines are based on this protein. In order to increase the efficacy of DNA immunogen encoding rabies virus glycoprotein, the construction of chimeric protein with the CD63 domain has been proposed. The CD63 is a transmembrane protein localized on the cell surface and in lysosomes. The lysosome targeting motif GYEVM is located at its C-terminus. We used the domain that bears this motif (c-CD63) to generate chimeric glycoprotein in order to relocalize it into lysosomes. Here, it was shown that, in cells transfected with plasmid that encodes glycoprotein with c-CD63 motif at the C-terminus, the chimeric protein was predominantly observed in lysosomes and at the cell membrane where the unmodified glycoprotein is localized in the endoplasmic reticulum and at the cell surface. We suppose that current modification of the glycoprotein may improve the immunogenicity of anti-rabies DNA vaccines due to more efficient antibody production.     

Induction of antigen-specific antibody response in human peripheral blood lymphocytes in vitro by a dog kidney cell vaccine against rabies virus (DKCV)

In the present report an in vitro method for obtaining a secondary human antibody response to a dog kidney cell vaccine against rabies virus (DKCV) is described. Cultures of peripheral blood mononuclear cells from normal rabies-immune and nonimmune donors were stimulated in vitro by DKCV. The production of virus-specific antibody in supernatant fluids was monitored by ELISA. Antibody was produced by lymphocytes from rabies-immune individuals, whereas those of nonimmune subjects consistently failed to produce anti-rabies antibodies after in vitro stimulation with DKCV. The generation of the anti-rabies virus antibody response of lymphocytes stimulated with DKCV was shown to be an antigen-dependent, as well as an antigen-specific process. Optimal antigen-specific responses were observed at relatively low concentrations of antigen (10(-1) to 10(-2) micrograms/culture). At increasing concentrations of antigen in culture (greater than 1 microgram/culture), the anti-rabies virus response was suppressed. Antibody produced upon stimulation was capable of neutralizing rabies virus. The response to rabies virus requires T cell help because lymphocytes depleted of SE rosetting cells did not respond to an antigenic stimulus. Studies in which the same individuals were followed over time showed a sequential development of circulating B cell subsets. The system may provide a model for the study of human B cell differentiation in vivo and in vitro and may be valuable for testing the potency of rabies vaccines in vitro.     

A DNA Construct That Encodes the Rabies Virus Consensus Glycoprotein with a Proteasome Degradation Signal Induces Antibody Production with IgG2A Subtype Predominance

The possibility of enhancing the immunogenicity of the rabies virus glycoprotein antigen encoded by a DNA vaccine has been investigated. Ubiquitin-like protein FAT10 has been attached to the N-terminus of the glycoprotein to target it to the proteasome and stimulate its presentation by MHC class I. Two forms of the protein, chimeric and original, have been detected in cells transfected with the DNA construct encoding the chimeric protein. The presence of the glycoprotein on the cell surface has been detected by immunostaining of transfected cells. The production of IgG and IgG2a antibodies has been more efficiently induced in mice immunized with the plasmid that encodes the chimeric protein than in those immunized with the plasmid that encodes unmodified glycoprotein. Moreover, the level of IgG2a antibodies exceeded the level of IgG1 antibodies, which indicates a preferential increase in the Th1 component of the immune response. The proposed DNA construct that encodes a modified glycoprotein with a proteasome degradation signal may be a promising DNA vaccine immunogen for post-exposure prophylaxis of rabies.     

狂犬病病毒糖蛋白的杆状病毒表达及其免疫原性研究

构建表达狂犬病病毒SRV9株糖蛋白(GP)的重组杆状病毒,评价其表达出的SRV9株糖蛋白对小鼠免疫效果。将狂犬病病毒SRV9株GP基因的完整开放阅读框克隆入穿梭质粒Bacmid中,构建重组穿梭质粒Bacmid-G,以此转染Sf9细胞。对病变细胞培养物进行电镜观察,获得正确重组杆状病毒后,通过Western-blot、IFA及小鼠免疫实验鉴定表达产物的免疫反应性及免疫原性。正确构建重组穿梭质粒Bacmid-G;获得表达SRV9株糖蛋白的重组杆状病毒,其表达产物具有良好免疫原性;表达产物接种小鼠可诱导其产生抗狂犬病病毒中和抗体,中和抗体达到保护水平的比例为100%。本实验所获得的重组杆状病毒表达出的SRV9株糖蛋白具有较好的免疫原性,可诱导小鼠产生保护性中和抗体,该实验为进一步开发狂犬病亚单位疫苗奠定了基础。     

Characterization of a human antibody fragment Fab and its calcium phosphate nanoparticles that inhibit rabies virus infection with vaccine

Recombinant antibody phage display technology has been used to mimic many aspects of the processes that govern the generation and selection of high-affinity natural human antibodies in the human immune system, especially for infectious disease prophylaxis. An anti-rabies virus immunized phage-display Fab library was constructed from peripheral blood lymphocytes from vaccinated volunteers. The immunized antibody library, with a diversity of 6.7×10(8), was used to select and produce antibodies that bound to rabies virus glycoprotein. After five rounds of immobilized fixed rabies virion panning, four unique DNA sequences were found in the higher binding clones, and only one, Fab094, showed neutralization activity. Fab094 components were analyzed by ELISA, immunoprecipitation and immunofluorescent staining. ELISA and immunofluorescence showed that Fab094 bound specifically to rabies virions. Immunoprecipitation and mass spectrometry showed that Fab094 reacted with rabies virus glycoprotein. To improve the penetration power of Fab094 antibodies, we developed Fab094 calcium phosphate nanoparticles (Fab094-CPNPs) and tested their efficacy. The rapid fluorescent focus inhibition test indicated that the neutralizing antibody titers of Fab094 and Fab094-CPNPs were reached at 200.17 IU/Kg and 246.12 IU/Kg, respectively. These findings were confirmed in vivo in a Kunming mouse challenge model. Our results demonstrate that human Fab094 and Fab094-CPNPs are efficacious candidate drugs to replace rabies immunoglobulin in post-exposure prophylaxis (PEP).     

狂犬病病毒糖蛋白表达及纯化及其记忆性B细胞结合能力的分析

表达纯化不同标签、不同大小3个狂犬病病毒糖蛋白,分析其结合功能后,得到具备高亲和力的、可特异性结合记忆性B细胞的狂犬病病毒糖蛋白。本实验通过基因工程的方法,采用不同的原核表达系统分别表达带有不同标签的、全长和膜外区的RVG,纯化蛋白并分析比较其结合功能,荧光标记候选蛋白,结合CD19及CD27的抗体,流式细胞术检测狂犬疫苗免疫后PBMCs中抗狂犬病病毒特异性记忆性B细胞的情况,确认候选蛋白与抗狂犬病毒特异性记忆性B细胞的结合功能。本实验成功构建了3个表达载体pGEX-5X-1-RVG、pET28a-RVG和pET30a-G,优化表达纯化条件成功获得了糖蛋白GST-RVG、His-RVG和His-G。纯化后的GST-RVG、His-RVG和His-G经Western blotting和ELISA鉴定均有抗原特异性;由竞争ELISA法测得3个纯化后糖蛋白与抗狂犬病病毒抗体的亲和力。通过流式细胞术可以检测到狂犬疫苗免疫后阳性志愿者PBMCs中的抗狂犬病病毒特异性记忆性B细胞,从而获得了高亲和力、可用于分选抗原特异性的记忆性B细胞的狂犬病病毒糖蛋白。     

狂犬病病毒抗体胶体金检测试纸的制备

通过胶体金免疫层析技术建立一种特异、便捷、快速的狂犬病病毒抗体检测方法,对犬等动物免疫狂犬病疫苗后的抗体水平监测提供参考。用醋酸锌沉淀法沉淀狂犬病病毒CVS11,Sepharose 4FF进行层析纯化。用柠檬酸三钠还原法制备的胶体金,标记纯化的狂犬病病毒,喷于试纸的结合释放垫 (金标垫),将SPA (葡萄球菌表面A蛋白) 和纯化的兔抗狂犬病病毒IgG分别喷于试纸的T (检测线) 处和C (对照线) 处,组装试纸条。用制备的试纸条对261份犬血清进行检测,与快速荧光灶抑制试验 (RFFIT) 检测的结果一致;对已知效价的犬狂犬病毒中和抗体 (VNA) 大于0.5 IU,结果为阳性;对狂犬病病毒中和抗体 (VNA) 小于0.5 IU/mL的血清,结果为阴性。制备的狂犬病病毒抗体胶体金检测试纸检测犬血清抗体,具有特异、便捷、快速的特点,能够检测出狂犬病病毒中和抗体大于0.5 IU的血清,适用于临床犬血清抗体水平监测,具有良好的应用前景。     

抗狂犬病毒中和抗体研究进展

狂犬病是一种人兽共患传染病,人和动物一旦发病后死亡率几乎百分之百,而有效的暴露后预防措施可以将死亡风险降至零。根据WHO推荐的狂犬病暴露后预防方案,一般狂犬病暴露者需要进行疫苗注射,严重者则需在进行疫苗注射的同时注射抗狂犬病毒中和抗体。常用的中和抗体有马抗狂犬病毒免疫球蛋白和人抗狂犬病毒免疫球蛋白,然而两者都存在引起过敏反应或血液疾病的风险。人源抗狂犬病毒中和抗体则因为具有安全性高、成本低、可量产等优点有望代替免疫球蛋白用于暴露后预防。基因工程抗体技术的发展加速了抗体人源化的进程。就抗狂犬病毒中和抗体的发展历程,不同类型中和抗体的优缺点以及中和抗体的未来研究方向作了综述及展望,以期为新一代狂犬疫苗的研发提供参考。     

Protection of mice from rabies by intranasal immunization with inactivated rabies virus.

The mucosal immunization method is a needle-free alternative way of vaccination. This study evaluated the efficacy of mucosal immunization for rabies. Mice were intranasally administered five times with inactivated and concentrated rabies virus antigen (CRV) supplemented with or without cholera toxin (CT). The anti-rabies virus antibody titer of mice intranasally immunized with CRV plus CT (CRV/CT) was comparable to that of mice intraperitoneally immunized twice with the same amount of CRV. Virus neutralizing (VNA) titers of mice immunized intranasally with CRV/CT were slightly lower than those of intraperitoneally immunized mice. Both anti-rabies virus ELISA antibody and VNA titers of mice immunized with CRV without CT were significantly lower than those of mice immunized with CRV/CT. In mice intranasally immunized with CRV/CT, and intraperitoneally immunized mice, high levels of IgG(2a) antibody were detected, suggesting the activation of Th1-driven cellular immunity by the two ways of immunization. All immunized mice were challenged intracerebrally with a lethal dose of virulent rabies virus CVS strain. The survival rates of mice immunized with CRV/CT and CRV without CT were 67% and 17%, respectively, while the rate of intraperitoneally immunized mice was 100%. Antigen-specific whole IgG and IgG(2a), and VNA titers of survived mice were significantly higher than those of dead mice at the challenge day. These data suggest the possibility of intranasal immunization with inactivated antigen as a rabies vaccination strategy and the importance of a mucosal adjuvant such as CT.     

Inactivated rabies vaccine control and release: use of an ELISA method.

Quality control of human rabies vaccines performed by National Control Laboratories (NCLs) prior to marketing vaccines batches requires in vivo and in vitro potency assays as requested by the relevant European Pharmacopoeia monographs, OMCLs guidelines and WHO technical recommendations.The aim of the present study was to check the suitability of an enzyme-linked immunosorbent assay (ELISA) using a virus neutralizing monoclonal antibody, directed to the rabies virus glycoprotein, to monitor the consistency of the lot to lot rabies vaccines production. Furthermore, this work was implemented to establish in house specifications for the glycoprotein content.     

狂犬病毒糖蛋白DNA疫苗的研制及其免疫效果的观察

构建了含有狂犬病毒（RV）CVS株糖蛋白（GP）基因的重组质粒pCMVCVSRG,将其转染至鼠NIH3T3细胞中,用间接免疫荧光法和APAAP法均证实RVGP能在真核细胞中表达。分别将合RV不同毒株的GP基因的质粒（DNA疫苗）及空白载体质粒（对照组）免疫小鼠,仅DNA疫苗免疫的小鼠产生了中和抗体。以RV攻击后,DNA疫苗免疫组小鼠的存活率与对照组相比,差异有极显著性意义（P＜0．01）;不同的启动子（CMV或SV40）与不同GP基因（来源于CVS株或ERA株）对DNA疫苗的免疫效果无明显影响。在注射120d后．用PCR方法仍可检测出RVGP基因。结果表明：狂犬病DNA疫苗能够诱生低水平的中和抗体和记忆性B淋巴细胞,并能保护小鼠抵抗RV的攻击。该疫苗能在体内稳定存在。狂犬病DNA疫苗的研制为狂犬病免疫开辟了一条新途径,并可为防治其他疾病的DNA疫苗的研制奠定基础。     

Correction: Neutralizing Antibody Response after Intramuscular Purified Vero Cell Rabies Vaccination (PVRV) in Iranian Patients with Specific Medical Conditions

Objective

Post exposure prophylaxis using one of the WHO-approved vaccines is the method of choice for preventing rabies. Abnormal immune function in patients with some specific medical conditions, such as pregnancy, chronic hepatitis B virus infection, different types of cancers like lymphoma, diabetes I and II, corticosteroid consumption by patients with rheumatoid arthritis and lupus erythematosus, could impair the immunologic response to various vaccines. The immune response to rabies vaccination has never been examined in patients with any of these described medical conditions. This study purposed to evaluate the neutralyzing antibody response after vaccination with purified Vero cell rabies vaccine (PVRV) according to the WHO-recommended Post–Exposure Prophylaxis (PEP) "ESSEN" regimen.

Methods

Thirty healthy volunteers and 50 volunteers with different medical conditions who were exposed to a suspected rabid animal in the 2nd or 3rd category of exposure received 5 doses of PVRV under the ESSEN protocol. Three blood samples were collected on days 0 (before the first dose), 14, and 35. The anti-rabies antibody titer was measured using the Rapid Fluorescent Foci Inhibition Test (RFFIT) and an ELISA Bio-Rad, Platelia, Rabies II kit.

Results

All subjects reached NAb titers above 0.5 IU/ml by day 14 after vaccination. On day 35 (1 week after receiving the last rabies vaccine), anti-rabies antibodies were in the protective level (>0.5 IU/ml) in both groups. There was no statistically significant difference in anti-rabies antibody response due to the type of exposure (category 2 or 3), and successful seroconversion was confirmed in both groups.

Conclusion

In conclusion, the ESSEN protocol using the PVRV vaccine is sufficient for rabies prophylaxis in patients with specific medical conditions.     

人狂犬病免疫球蛋白使用效果观察

为了解人狂犬病免疫球蛋白的作用效果,我们将观察对象随机分成了A、B、C三组,分别采用三种措施进行狂犬病的预防治疗,即：A组联合使用狂犬病疫苗与人狂犬病免疫球蛋白;B组联合使用狂犬病疫苗与抗狂犬病血清(马源);C组仅注射狂犬病疫苗,并采用小鼠中和试验对这三组成员在免疫后3、7、14、45天及1年时的中和抗体水平进行检测。结果表明：狂犬病疫苗与人狂犬病免疫球蛋白或抗狂犬病血清联合使用,可使体内更早出现抗狂犬病的中和抗体。注射人狂犬病免疫球蛋白后未发生临床副反应。     

Prevention of rabies virus infection in dogs by a recombinant canine adenovirus type-2 encoding the rabies virus glycoprotein

Safe and effective vaccination is important for rabies prevention in animals. Although several genetically engineered rabies vaccines have been developed, few have been licensed for use, principally due to biosafety concerns or due to poor efficacy in animal models. In this paper, we describe the construction and characterization of a replication-competent recombinant canine adenovirus type-2 expressing the rabies virus glycoprotein (SRV9 strain) by a different strategy from that reported previously, i.e., the recombinant genome carrying the glycoprotein cDNA was generated by a series of strictly gene cloning steps, infectious recombinant virus was obtained by transfecting the recombinant genome into a canine kidney cell line, MDCK. This recombinant virus, CAV-E3delta-CGS, was subcutaneously injected into dogs. All vaccinated dogs produced effective neutralizing antibodies after one inoculation and a stronger anamnestic immune response was produced after booster injection. The immunized dogs could survive the challenge of 60,000 mouse LD50 CVS-24, which is lethal to all unimmunized dogs and is comparable to the conventional vaccines. The immunity lasts for months with a protective level of neutralizing antibody. This recombinant virus would be an alternative to the attenuated and the inactivated rabies vaccines and be prospective in immunizing dogs against rabies.     

Use of a monoclonal antibody for quantitation of rabies vaccine glycoprotein by enzyme immunoassay

The use of a monoclonal antibody specific for the envelope glycoprotein of rabies virus has been used in a direct enzyme immunoassay to quantify the glycoprotein content of rabies vaccines produced in two kinds of cell culture. The results of this direct enzyme immunoassay are well correlated with the in vivo NIH potency test. This test may be a useful tool to rapidly and accurately control the antigenic value of a vaccine. It could also be used for the "in process' control of vaccine production before deciding whether a vaccine batch may reasonably be subjected to the NIH potency test.     

Preparation and identification of anti-rabies virus monoclonal antibodies

To provide a foundation for the development of rapid and specific methods for the diagnosis of rabies virus infection,anti-rabies virus monoclonal antibodies were prepared and rabies virus nucleoprotei...     

人源抗狂犬病毒中和性全抗体在昆虫细胞中的表达

将来源于噬菌体抗体库的人源狂犬病毒糖蛋白特异性单抗G10Fab的基因 ,克隆入杆状病毒人源IgG抗体表达载体 ,通过转染将重组质粒导入昆虫细胞 ,以全抗体的形式表达了一株人源抗狂犬病毒基因工程抗体G10。用亲和层析的方法纯化了表达产物 ,经与一株鼠源糖蛋白特异性单抗竞争证实 ,该单克隆抗体特异性识别狂犬病毒糖蛋白 ,亲和力约为 10 -9M。体外中和实验证明 ,该单抗对狂犬病毒aG株具有体外中和活性     

Novel, chimpanzee serotype 68-based adenoviral vaccine carrier for induction of antibodies to a transgene product

An E1-deletion-containing adenoviral recombinant based on the chimpanzee serotype 68 (AdC68) was developed to express the rabies virus glycoprotein. Mice immunized with this construct (AdC68rab.gp) developed antibodies to rabies virus and remained resistant to challenge with an otherwise lethal dose of rabies virus. In na?ve mice immunized intranasally, the rabies virus-specific antibody responses elicited by AdC68rab.gp were comparable with regard to both titers and isotype profiles to those induced by an adenoviral recombinant based on human serotype 5 (Adhu5) expressing the same transgene product. In contrast, subcutaneous immunization with the AdC68rab.gp vaccine resulted in markedly lower antibody responses to the rabies virus glycoprotein than the corresponding Adhu5 vaccine. Antibodies from AdC68rab.gp-immunized mice were strongly biased towards the immunoglobulin G2a isotype. The antibody response to the rabies virus glycoprotein presented by Adhu5rab.gp was severely compromised in animals preexposed to the homologous adenovirus. In contrast, the rabies virus-specific antibody response to the AdC68rab.gp vaccine was at most marginally affected by preexisting immunity to common human adenovirus serotypes, such as 2, 4, 5, 7, and 12. This novel vaccine carrier thus offers a distinct advantage over adenoviral vaccines based on common human serotypes.     

Post-exposure Treatment with Anti-rabies VHH and Vaccine Significantly Improves Protection of Mice from Lethal Rabies Infection

Post-exposure prophylaxis (PEP) against rabies infection consists of a combination of passive immunisation with plasma-derived human or equine immune globulins and active immunisation with vaccine delivered shortly after exposure. Since anti-rabies immune globulins are expensive and scarce, there is a need for cheaper alternatives that can be produced more consistently. Previously, we generated potent virus-neutralising VHH, also called Nanobodies, against the rabies glycoprotein that are effectively preventing lethal disease in an in vivo mouse model. The VHH domain is the smallest antigen-binding functional fragment of camelid heavy chain-only antibodies that can be manufactured in microbial expression systems. In the current study we evaluated the efficacy of half-life extended anti-rabies VHH in combination with vaccine for PEP in an intranasal rabies infection model in mice. The PEP combination therapy of systemic anti-rabies VHH and intramuscular vaccine significantly delayed the onset of disease compared to treatment with anti-rabies VHH alone, prolonged median survival time (35 versus 14 days) and decreased mortality (60% versus 19% survival rate), when treated 24 hours after rabies virus challenge. Vaccine alone was unable to rescue mice from lethal disease. As reported also for immune globulins, some interference of anti-rabies VHH with the antigenicity of the vaccine was observed, but this did not impede the synergistic effect. Post exposure treatment with vaccine and human anti-rabies immune globulins was unable to protect mice from lethal challenge. Anti-rabies VHH and vaccine act synergistically to protect mice after rabies virus exposure, which further validates the possible use of anti-rabies VHH for rabies PEP.     

A simple immuno-capture ELISA to estimate rabies viral glycoprotein antigen in vaccine manufacture.

Rabies is an endemic, fatal zoonotic disease in the developing countries. Prevention and post-exposure therapy require safe and efficacious vaccines. The vaccine potency depends on the amount of immunogenic rabies viral glycoprotein antigen in the vaccine preparation. In order to estimate the rabies viral glycoprotein antigen, a specific monoclonal antibody was developed and used in an immuno-capture ELISA (IC-ELISA). The monoclonal antibody binds a conformational epitope on the natively folded rabies viral glycoprotein as indicated by specific, membrane fluorescence on unfixed, rabies virus infected murine neuroblastoma (MNA) cells and glycoprotein gene encoding plasmid transfected COS cells. In addition, the monoclonal antibody competes with and blocks a glycoprotein antigen site III binding monoclonal antibody (mAb-D1, Institut Pasteur, Paris, France). The monoclonal antibody was used in an IC-ELISA using an in-house standard to quantify the rabies viral glycoprotein antigen in 12 vaccine preparations with potency values ranging from 4 to 18 IU. The results indicated a good correlation with the NIH mouse potency assay (r=0.83). The immuno-capture ELISA described in this study can be used to quantify the immunogenic rabies viral glycoprotein antigen in the inactivated rabies viral antigen preparation in a simple and rapid format, which enables better vaccine formulation.