DnaK and DnaJ heat shock proteins participate in protein export in Escherichia coli.

In Escherichia coli secreted proteins must be maintained in an export-competent state before translocation across the cytoplasmic membrane. This function is carried out by a group of proteins called chaperones. SecB is the major chaperone that interacts with precursor proteins before their secretion. We report results indicating that the DnaK and DnaJ heat shock proteins are also involved in the export of several proteins, most likely by acting as their chaperones. Translocation of alkaline phosphatase, a SecB-independent protein, was inhibited in dnaK- and dnaJ- mutant strains, suggesting that export of this protein probably involves DnaK and DnaJ. In addition, DnaK and DnaJ play a critical role in strains lacking SecB. They are required both for viability and for the residual processing of the SecB-dependent proteins LamB and maltose-binding protein (MBP) seen in secB null strains. Furthermore, overproduction of DnaK and DnaJ permits strains lacking SecB to grow in rich medium and accelerates the processing of LamB and MBP. These results suggest that under conditions where SecB becomes limiting, DnaK and DnaJ probably substitute for SecB and facilitate protein export. This provides the cell with a mechanism to overcome a temporary imbalance in the secretion process caused by an abrupt expansion in the pool of precursor proteins.     

快速深低温冻存对新生大鼠卵巢组织免疫原性的影响

目的:探讨快速冻存法冻存新生大鼠卵巢器官的效果,以及冻存对卵巢抗原性的影响。方法:采用快速冻存法冻存出生1 d的鼠(新生鼠)卵巢组织,移植入同系去卵巢成年雌性大鼠的肾被膜下,利用免疫组织化学方法及Western blot检测观察移植物内CD8 和CD4 T淋巴细胞的浸润情况。结果:新生鼠卵巢组织移植后动情周期恢复率(66.67%)低于新鲜移植组(90.51%),但无显著性差异。各移植物内毛细血管丰富;有正常发育阶段的各级卵泡、间质腺及闭锁卵泡;CD8 和CD4 阳性细胞计数值及其蛋白表达明显低于新鲜移植组。结论:快速冻存法可有效地冻存新生鼠的卵巢;冻存降低新生鼠卵巢组织抗原性。     

Antigenicity and immunogenicity of recombinant glutamate-rich protein of Plasmodium falciparum expressed in Escherichia coli.

A recombinant Plasmodium falciparum glutamate-rich protein (GLURP) was produced in Escherichia coli as a nearly full-length protein. In order to map immunodominant regions on GLURP, the nonrepetitive amino-terminal region (R0) as well as the central repeat region (R1) and the carboxy-terminal repeat region (R2) were also produced as separate products. All four purified gene products reacted specifically with serum samples from adults living in an area of Liberia where malaria is holoendemic. It appears that the human immune response against GLURP is primarily directed against the R2 region because 94% of the serum samples reacted with this region in an immunoassay. Antibody reactivity against the R0 region was also observed in 75% of the serum samples, while the R1 region showed only weak antibody-binding activity. When the nearly full-length GLURP molecule was adsorbed to Al(OH)3 it was found to be immunogenic in mice. In these experiments, the antibody response was almost exclusively directed against the R2 region. When anti-GLURP sera were obtained from rabbits immunized with the three regions, R0, R1, and R2, respectively, they recognized in immunoprecipitation experiments authentic GLURP from P. falciparum grown in vitro. These results demonstrate that GLURP produced in E. coli can induce a humoral immune response against GLURP derived from blood-stage parasites.     

小鼠神经干细胞免疫原性的研究

目的:探讨小鼠神经干细胞(NSCs)免疫原性,以利于解决神经干细胞移植中的免疫排斥问题。方法:(1)首先将30只C57BL/6近交系小鼠随机分成两组,以BALB/c近交系小鼠的NSCs及肝细胞(作为体细胞对照组)分别进行腹腔主动免疫,然后将NSCs及肝细胞分别与各自免疫后小鼠的T淋巴细胞进行单向混合淋巴细胞培养,通过液闪计数仪检测各自T淋巴细胞增殖程度,从而比较两者免疫原性的强弱。(2)利用异硫氰酸荧光素标记抗体(FITC)及Phycoery-thrin(PE)抗体分别标记BALB/c小鼠NSCs主要组织相容性抗原复合物Ⅰ、Ⅱ(MHC-Ⅰ、MHC-Ⅱ),然后通过流式细胞术(FCM)分别检测BALB/c小鼠NSCs及其肝细胞的MHC-Ⅰ和MHC-Ⅱ阳性细胞比例,从而推断小鼠NSCs的免疫原性。结果:(1)NSC组液闪计数仪检测所得cpm值为16592.8±2865.3,肝细胞组为27815.0±2416.3,NSC组明显低于肝细胞组,差别有统计学意义(P0.01)。(2)小鼠NSCs实验组中,约(87.55±3.65)%的增殖期神经干细胞没有检测到MHC-Ⅰ和MHC-Ⅱ分子表达;而作为对照组的小鼠肝细胞组中,仅有约(27.45±1.86)%的肝细胞未表达MHC-Ⅰ和MHC-Ⅱ分子。且NSC组MHC-Ⅰ和MHC-Ⅱ阴性细胞比例明显高于肝细胞组,差别有统计学意义(P0.01)。结论:小鼠神经干细胞具有较弱的免疫原性,且其免疫原性明显低于同一个体的肝细胞。     

国产流行性感冒病毒疫苗免疫原性研究的meta分析

目的 评价国产流行性感冒(简称流感)病毒疫苗的免疫原性.方法 通过文献检索搜集2012年9月前发表的有关国产与进口流感病毒疫苗免疫原性比较研究的文献,利用Stata10.0软件进行meta分析.结果 共有20篇符合标准的文献纳入本研究.结果显示:国产流感病毒疫苗B型抗体阳转率显著高于进口流感病毒疫苗(P=0.036,RR=1.036,95％ CI:1.002～1.070),未发现国产流感病毒疫苗3个亚型的保护率及H1N1和H3N2抗体阳转率与进口流感病毒疫苗存在显著差异(P＞0.05).进一步的亚组分析发现:国产流感全病毒灭活疫苗B型抗体阳转率(P=0.024,RR=1.040,95％CI:1.005～ 1.077)及保护率(P=0.031,RR =1.059,95％CI:1.005～1.116)、H3N2抗体(P=0.019,RR=1.053,95％ CI:1.009 ～1.098)保护率均显著高于进口流感病毒疫苗.结论 国产流感病毒疫苗具有较好的免疫原性.     

Solubility, immunogenicity and physical properties of the nucleocapsid protein of Nipah virus produced in Escherichia coli

The nucleocapsid (N) protein of Nipah virus (NiV) can be produced in three Escherichia coli strains [TOP10, BL21(DE3) and SG935] under the control of trc promoter. However, most of the product existed in the form of insoluble inclusion bodies. There was no improvement in the solubility of the product when this protein was placed under the control of T7 promoter. However, the solubility of the N protein was significantly improved by lowering the growth temperature of E. coli BL21(DE3) cell cultures. Solubility analysis of N- and C-terminally deleted mutants revealed that the full-length N protein has the highest solubility. The soluble N protein could be purified efficiently by sucrose gradient centrifugation and nickel affinity chromatography. Electron microscopic analysis of the purified product revealed that the N protein assembled into herringbone-like particles of different lengths. The C-terminal end of the N protein contains the major antigenic region when probed with antisera from humans and pigs infected naturally.     

人免疫缺陷病毒1型(HIV-1)gag基因疫苗的免疫原性

目的 :检测人免疫缺陷病毒 1型 (HIV 1)gag基因疫苗的免疫原性。方法 :分别以ELISA、荧光抗体染色和乳酸脱氢酶释放法 ,检测免疫小鼠血清抗体滴度、脾T细胞亚群的数量和淋巴细胞杀伤效应。结果 :血清抗体滴度、脾T细胞亚群的数量及淋巴细胞杀伤效应 ,重组质粒pVAXGAG免疫组与空载体pVAX1对照组相比较差异显著(分别为P <0 .0 5和P <0 .0 1)。结论 :HIV 1DNA疫苗质粒pVAXGAG在BALB/c小鼠中不仅可诱导特异性体液免疫 ,而且可诱导特异性细胞免疫。     

Reflections on the immunogenicity of therapeutic proteins

Therapeutic proteins are now established as a major class of medication with proven efficacy in treating a wide range of diseases. The administration of such proteins to patients can lead to the development of antibodies that are able to bind and eventually neutralise the protein administered. Many advances have been made in understanding the immunogenicity of therapeutic proteins, but opinions are often conflicting. Although it is important to understand more about the antibodies generated against therapeutic proteins, the need for future research must not be neglected, so that other relevant factors can be identified and addressed to maximise treatment benefits for patients.     

艰难梭菌细胞毒素B功能区的原核表达及免疫原性

目的纯化已表达艰难梭菌(CD)细胞毒素B羧基末端受体结合区(CD3)的基因,并检测其免疫原性。方法PCR克隆目的基因到表达载体pET22b( ),重组质粒转化到E.coliBL21(DE3),经IPTG诱导表达,利用金属螯合色谱层析方法纯化后,SDS-PAGE方法对纯化蛋白进行分析。并检测其免疫反应性。结果成功表达的是分子质量约为71.3 ku的重组蛋白,占菌体总蛋白的34%,可溶性表达占上清的22.7%,包涵体占沉淀的25.7%。重组蛋白纯化后可溶性蛋白浓度为0.781 g/L。并与抗毒素B抗体具有良好的免疫原性。结论成功克隆了CD3基因,构建的重组质粒可高效表达CD3重组蛋白,为CD相关性疾病的诊断及后期制备疫苗,提供了有力的保障。     

CesD2 of enteropathogenic Escherichia coli is a second chaperone for the type III secretion translocator protein EspD

Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli are extracellular pathogens that employ a type III secretion system to export translocator and effector proteins, proteins which facilitates colonization of the mucosal surface of the intestine via formation of attaching and effacing (A/E) lesions. The genes encoding the proteins for A/E lesion formation are located on a pathogenicity island, termed the locus of enterocyte effacement (LEE), which contains eae encoding intimin as well as the type III secretion system and effector genes. Many type III secreted proteins are stabilized and maintained in a secretion-competent conformation in the bacterial cytosol by specific chaperone proteins. Three type III chaperones have been described thus far within the EPEC LEE region: CesD, for the translocator proteins EspB and EspD; CesT, for the effector proteins Tir and Map; and CesF, for EspF. In this study we report the characterization of CesD2 (previously Orf27), a second LEE-encoded chaperone for EspD. We show specific CesD2-EspD protein interaction which appears to be necessary for proper EspD secretion in vitro and pathogenesis in vivo as demonstrated in the A/E-lesion-forming mouse pathogen Citrobacter rodentium.     

The effect of haptens on protein‐carrier immunogenicity

The immune response against hapten is T‐cell‐dependent, and so requires the uptake, processing and presentation of peptides on MHC class II molecules by antigen‐presenting cells to the specific T cell. Some haptens, following conjugation to the available free amines on the surface of the carrier protein, can reduce its immunogenicity. The purpose of this study was to explore the mechanism by which this occurs. Four proteins were tested as carriers and six molecules were used as haptens. The immune response to the carrier proteins was reduced > 100‐fold by some of the haptens (termed carrier immunogenicity reducing haptens – CIRH), whereas other haptens did not influence the protein immunogenicity (carrier immunogenicity non‐reducing haptens – nCIRH). Conjugation of the protein to a CIRH affected protein degradation by lysosomal cathepsins, leading to the generation of peptides that differ in length and sequence from those derived from the same native protein or that protein modified with nCIRH. Injection of CIRH‐conjugated protein into mice induced an increase in the population of regulatory T cells. The results of this study provide a putative mechanism of action for the reduction of immune response to haptenated proteins.     

A final report on safety and immunogenicity of a bivalent aqueous subunit HBV vaccine

The bivalent form of an aqueous formalin-inactivated hepatitis B vaccine was evaluated for safety and immunogenicity in chimpanzees. To evaluate safety five animals were inoculated intravenously with vaccine containing 500 micrograms HBsAg and two animals with 50 micrograms. None of these animals developed hepatitis or any serologic marker indicative of the presence of residual live virus in the vaccine. Twenty-four animals were used to evaluate immunogenicity and protective efficacy. Seven of these immunized animals produced weak or no anti-HBs responses. Two doses of 50 micrograms HBsAg given subcutaneously 1 month apart protected each of four animals that were challenged with 10(3.5) CID50 HBV at 6 and 12 months after immunization and protected three of four animals challenged at 24 months against development of hepatitis or HBsAg. Three of 4 animals in each group immunized with two doses of 20, 10, or 5 micrograms HBsAg were similarly protected when challenged 6 months after immunization. Thirteen of 20 immunized animals that did not develop HBsAg after challenge with HBV developed anamnestic anti-HBs or anti-HBc responses between 2 and 18 months after challenge, indicating minimal replication of challenge virus. The time of onset and frequency of occurrence of these delayed responses was related to the titer of anti-HBs at the time of challenge. False positive Ausab test results were observed in quarantined chimpanzees. These were neither preceded by appearance of HBsAg nor accompanied by development of anti-HBc. In most cases these reactions were due to a reactant having a sedimentation coefficient and an electrophoretic mobility resembling that of IgM. This reactant generally did not appear to confer resistance to challenge with HBV. The humoral immune response was characterized as being entirely of the IgM class 2 weeks after immunization and switched entirely into the IgG class by 10-12 weeks after vaccine administration. At the time of challenge all animals with antibody had anti-HBs of subtype a.     

Human IgG Fc promotes expression,secretion and immunogenicity of enterovirus 71 VP1 protein

Enterovirus (EV71) can cause severe neurological diseases, but the underlying pathogenesis remains unclear. The capsid protein, viral protein 1 (VP1), plays a critical role in the pathogenicity of EV71. High level expression and secretion of VP1 protein are necessary for structure, function and immunogenicity in its natural conformation. In our previous studies, 5 codon-optimized VP1 DNA vaccines, including wt-VP1, tPA-VP1, VP1-d, VP1-hFc and VP1-mFc, were constructed and analyzed. They expressed VP1 protein, but the levels of secretion and immunogenicity of these VP1 constructs were significantly different (P<0.05). In this study, we further investigated the protein levels of these constructs and determined that all of these constructs expressed VP1 protein. The secretion level was increased by including a tPA leader sequence, which was further increased by fusing human IgG Fc (hFc) to VP1. VP1-hFc demonstrated the most potent immunogenicity in mice.Furthermore, hFc domain could be used to purify VP1-hFc protein for additional studies.     

产肠毒素大肠杆菌(ETEC)的两种抗原制品对蛋鸡免疫原性的对比研究

目的：采用产肠毒素大肠杆菌（ETEC）K88标准菌株，研究其不同浓度的菌毛及全菌两种抗原对蛋鸡的免疫原性，并确定最佳的抗原浓度。方法：用SDS—PAGE鉴定菌毛蛋白的纯度，通过间接ELISA法检测特异性卵黄抗体（IgY）的效价。结果：菌毛蛋白对蛋鸡的免疫原性优于全菌；纯化的菌毛蛋白对蛋鸡的免疫原性优于粗菌毛蛋白，其诱导的抗体效价最高可达1：480000，初免84天后未见有明显的下降趋势；菌毛蛋白最佳浓度为2mg／ml，全菌最佳浓度为10^10cfu／ml。结论：本研究为制备高效价特异性IgY抗体奠定了基础。     

Role of antigen-presenting cells in variation in immunogenicity of mycobacteria.

The route of immunization was observed to play a significant role in deciding the outcome of immunization with killed mycobacterial vaccines. Whereas the slow growers were immunogenic by both intraperitoneal and intradermal routes, the rapid growers were immunogenic only by intradermal route. The non-responder state of mice to Mycobacterium vaccae by i.p. route of immunization could be corrected by prior treatment with poly I:poly C, an interferon inducer, or indomethacin, a prostaglandin inhibitor. Antigen-presenting efficiency of peritoneal and spleen cells were compared employing M. vaccae and M. tuberculosis H37Rv primed T cells and corresponding sonicates as antigens in an in vitro lymphocyte transformation test. Irradiated spleen cells presented both the antigens efficiently. However, with peritoneal cells as antigen-presenting cells, proliferative response against only M. tuberculosis was observed; proliferation of M. vaccae primed T cells was very poor. Peritoneal cells of poly I:poly C treated mice showed distinct improvement in their efficiency of presentation; even paraformaldehyde-fixed peritoneal cells gave an efficient stimulation with M. vaccae. The percentage of Ia-positive fraction in peritoneal cells was very low (5.95%) in comparison with spleen cells (38.37%). Poly I:poly C treatment resulted in increase in the Ia-positive cell fraction of the peritoneal cells to 24.5%.     

The potential of polymeric nanoparticles to increase the immunogenicity of the hapten clenbuterol

Micro‐ and nanoparticles prepared from the biodegradable and biocompatible polymers poly(lactide‐co‐glycolide) (PLGA) and polymethylmethacrylate (PMMA) have been successfully used as immunopotentiating antigen delivery systems. In our study, this approach was used to improve polyclonal antibody production to clenbuterol (CBL), a model hapten. PLGA and PMMA nanoparticles were loaded with either CBL alone or with a clenbuterol‐transferrin conjugate (CBL—Tfn) and administered subcutaneously to mice. PLGA nanoparticles were administered with or without the saponin adjuvant Quil A. The anti‐CBL titres present in experimental sera were determined by an enzyme immunoassay (ELISA). CBL‐Tfn‐loaded PLGA nanoparticles co‐administered with Quil A had obvious advantages immunologically over the currently used method of raising antibodies to CBL (the positive control). The combined adjuvanticity of Quil A and PLGA nanoparticles resulted in a positive response in all four of the mice tested and in higher antibody titres than were seen in the positive control group. Furthermore, the sustained release of immunogen from the nanoparticles permitted a reduction in immunizing frequency over the 15‐week study period.     

Safety and immunogenicity of a prototype enterotoxigenic Escherichia coli vaccine administered transcutaneously

Transcutaneous immunization (TCI) is a new method for vaccine delivery that has been shown to induce immunity relevant to enteric disease vaccines. We evaluated the clinical safety and immunogenicity of a recombinant subunit vaccine against enterotoxigenic Escherichia coli (ETEC) delivered by TCI. Adult volunteers received patches containing the recombinant ETEC colonization factor CS6, either with heat-labile enterotoxin (LT) or patches containing CS6 alone. The vaccine was administered at 0, 1, and 3 months, and serum antibodies and antibody-secreting cells (ASCs) were assessed. Among the 26 volunteers that completed the trial, there were no responses to CS6 in the absence of LT. In the groups receiving both CS6 and LT, 68 and 53% were found to have serum anti-CS6 immunoglobulin G (IgG) and IgA, respectively; 37 and 42% had IgG and IgA anti-CS6 ASCs. All of the volunteers receiving LT had anti-LT IgG, and 90% had serum anti-LT IgA; 79 and 37% had anti-LT IgG and IgA ASCs. Delayed-type hypersensitivity (DTH), suggesting T-cell responses, was seen in 14 of 19 volunteers receiving LT and CS6; no DTH was seen in subjects receiving CS6 alone. This study demonstrated that protein antigens delivered by a simple patch could induce significant systemic immune responses but only in the presence of an adjuvant such as LT. The data suggest that an ETEC vaccine for travelers delivered by a patch may be a viable approach worthy of further evaluation.