GPI锚定蛋白与白血病

羧基末端结合有糖基化磷脂酰肌醇(GPI)结构的膜蛋白,称为GPI锚定蛋白(glycosylphosphatidy-linositol-anchored protein);它们功能广泛,涉及细胞识别、生长、分化和程序性死亡等重要生命过程,与许多疾病有着一定的联系.人体内水解GPI锚定蛋白中的肌醇磷酸酯键的只有糖基化磷脂酰肌醇特异性磷脂酶D(glycosylphosphatidy-linositol spe-cific phospholipaseD GPI-PLD).本文概述了近年来有关GPI锚定蛋白的研究状况,包括它的结构、组成、功能和水解酶GPI-PLD,GPI锚定蛋白与白血病的发生、发展及治疗等的相关性研究.     

间日疟原虫疫苗候选抗原Pvs25的基因分析

目的了解我省疟疾患者间日疟原虫分离株传播阻断疫苗候选抗原Pvs25基因多态性,为疟疾疫苗的开发与应用提供依据.方法从间日疟原虫感染患者血样制备的滤纸血膜中提取疟原虫基因组DNA,对Pvs25基因进行PCR扩增、纯化和直接序列分析.结果所获13个全长为646bp的Pvs25基因序列,与间日疟原虫标准株Sal-1相比,Pvs25全长序列中在核苷酸水平上有2处点突变,为错义突变,产生2种基因型;在氨基酸水平引起相应氨基酸替换.结论浙江样本中间日疟原虫Pvs25基因型有二型,与国内报道的相同,基因多态性少,因此这种抗原组份有可能成为一种疟疾疫苗理想的候选抗原.     

抗子孢子疫苗的研究进展

抗子孢子疫苗的研究进展潘赛贻综述黄祺林审校由于疟原虫的抗药性和媒介按蚊的抗药性，人们寻找新的疟疾防治方法，其中疟疾疫苗的研制是人们的主要兴趣之一．分子生物学和免疫学技术的发展为疟疾疫苗的研制开拓了广阔前景。制备疟疾疫苗现有三种策略，第一种策略为利用全...     

疟疾疫苗研究进展

研究安全有效的免疫方法防治疟疾是免疫学家为之奋斗了 6 0多年的课题。由于疟原虫和传播媒介对药物和杀虫剂抗性的迅速发展 ,疟疾疫苗对控制全球疟疾的作用显得更加重要。目前 ,所有疟疾疫苗的研究几乎都集中在恶性疟(Plasmodium falciparum ) ,它是引起死亡的主要疟原虫种。免疫学方法预防疟疾十分复杂 ,经过几十年的研究结果表明 ,疟疾获得性免疫有两种 ,生命周期特异性和株特异性 ,疟疾学家对选择那一种途径作为疫苗最有效 ,还未达成一致意见。目前疟疾疫苗的大部分研究都是针对种特异性、生活周期特异性、株特异性。但也有一些疟疾学…     

疟疾疫苗的展望

回顾了在不同宿主—疟原虫系统中用佐剂抗原疫苗预防无性期疟原虫获得的资料。根据这些资料考虑了与抗疟疾疫苗发展和试验有关的问题。对诱发免疫佐剂的要求和需要的佐剂类型主要取决于宿主。由于不知道人对疟疾疫苗的免疫反应,所以尚不能预言哪种动物感染最可能是人疟的可靠模型,虽然一般假定猴是最适当的类似物。因此细心研究猴对纯化疟疾抗原的免疫反应对发展用于人体试验的疫苗是必要的。     

疟原虫在人体内发育过程的研究进展

疟疾是由疟原虫引起的虫媒传染病，在全球尤其是热带地区肆虐流行，严重威胁着人类的健康。疟原虫主要在人类宿主体内发育繁殖，具有复杂的生命周期，包括疟原虫入侵、迁移、逃避免疫攻击、肝细胞内分裂增殖、入侵红细胞并在红细胞内大量繁殖、周期性释放等系列过程，最终导致疟疾患者症状周期性发作。本文重点围绕疟原虫（即子孢子、裂殖子）人体红细胞外、红细胞内入侵及发育过程的研究进展进行综述，为疟疾疫苗研发和疟疾防控救治提供参考。     

世卫组织决定:送首款疟疾疫苗进非洲

人类的抗疟史又迈进了一大步. 近日,世界卫生组织做出重大决定:建议推广疟疾疫苗,以保护非洲儿童. 这是世界首款疟疾疫苗. 早在上世纪80年代,该款疫苗就已被首次开发,只是它不完美:需注射4剂,且仅能对儿童的严重疟疾提供大约30％的保护. 保护率低,是它一直没有被推广的主要原因. 然而,疟疾不是小病. 虽然我国已消除了疟疾,但在非洲、东南亚、南美洲等地,恶性疟疾仍旧折磨着孩童们. 疟疾,是一种蚊虫传播疾病,患者感染疟原虫后,出现寒战、高热等反应,可危及全身器官,只能靠及时治疗保命.     

疟疾疫苗研究进展

疟疾是一种世界范围内的传染病,严重影响人类的身体健康和生命安全.疫苗作为控制乃至消灭传染病的有效手段,在疟疾研究中受到广泛关注.目前针对疟原虫生活史各期的期特异性疫苗、传播阻断型疫苗、多阶段/多抗原疫苗以及减毒活疫苗都处于研究中.尽管尚无成熟疫苗推入市场,但一些候选疫苗已进入临床实验,并产生了非常有希望的结果.该文就疟疾疫苗的研究进展做一综述.     

血吸虫病疫苗的进展

有关疟原虫抗原的鉴定和有前途的疟疾疫苗临床试验的快速进展最近不乏报道。同时对于控制另一个主要寄生虫性疾病——血吸虫病的实验研究也同样取得了成功性的进展。在世界卫生组织最近的一次会议上(1986)已指出对该病的免疫学研究是成功     

恶性疟原虫杂合多价抗原免疫活性初步研究──IL-2测定

将β－半乳糖苷酶、ＨＢｓＡｇ以及恶性疟原虫两种重组复合抗原ＨＢｓＡｇ／４５肽与β－半乳糖苷酶／４５肽分别免疫小鼠。然后测定免疫小鼠脾细胞在ＣｏｎＡ和恶性疟原虫红内期全虫抗原诱导下产生ＩＬ－２的水平。结果表明，ＨＢｓＡｇ／４５肽免疫组ＩＬ－２水平明显高于β－半乳糖苷酶／４５肽免疫组。结果提示，ＨＢｓＡｇ颗粒有可能成为疟疾疫苗良好的蛋白载体。     

Maternal immunization and malaria in pregnancy

Malaria in pregnancy is a major cause of poor outcomes for both mother and fetus, and malaria-induced low birth weight (LBW) may kill nearly 400,000 African infants each year. The hallmark of pregnancy malaria due to Plasmodium falciparum is the sequestration of infected erythrocytes (IEs) in the placenta. Malaria can suppress responses to immunogens, and placental malaria can impair materno-fetal antibody transfer, potentially reducing the benefits of maternal immunization strategies. Parasites infecting the placenta have been shown to have distinct adhesive and antigenic features. Women become resistant to pregnancy malaria over successive pregnancies as they acquire antibodies that recognize placental parasites, suggesting that a vaccine is feasible. Serologic evidence indicates that the target for such a vaccine is antigenically conserved, and surface proteins expressed by placental parasites have been identified as vaccine candidates. Because malaria suppresses vaccine responses and reduces the transfer of maternal antibodies to the fetus, the prevention of pregnancy malaria may benefit maternal immunization strategies that protect neonates from infections other than malaria.     

Cross-stage immunity for malaria vaccine development

A vaccine against malaria is urgently needed for control and eventual eradication. Different approaches are pursued to induce either sterile immunity directed against pre-erythrocytic parasites or to mimic naturally acquired immunity by controlling blood-stage parasite densities and disease severity. Pre-erythrocytic and blood-stage malaria vaccines are often seen as opposing tactics, but it is likely that they have to be combined into a multi-stage malaria vaccine to be optimally safe and effective.Since many antigenic targets are shared between liver- and blood-stage parasites, malaria vaccines have the potential to elicit cross-stage protection with immune mechanisms against both stages complementing and enhancing each other. Here we discuss evidence from pre-erythrocytic and blood-stage subunit and whole parasite vaccination approaches that show that protection against malaria is not necessarily stage-specific. Parasites arresting at late liver-stages especially, can induce powerful blood-stage immunity, and similarly exposure to blood-stage parasites can afford pre-erythrocytic immunity.The incorporation of a blood-stage component into a multi-stage malaria vaccine would hence not only combat breakthrough infections in the blood should the pre-erythrocytic component fail to induce sterile protection, but would also actively enhance the pre-erythrocytic potency of this vaccine. We therefore advocate that future studies should concentrate on the identification of cross-stage protective malaria antigens, which can empower multi-stage malaria vaccine development.     

Antibodies against a Plasmodium falciparum antigen PfMSPDBL1 inhibit merozoite invasion into human erythrocytes

One approach to develop a malaria blood-stage vaccine is to target proteins that play critical roles in the erythrocyte invasion of merozoites. The merozoite surface proteins (MSPs) and the erythrocyte-binding antigens (EBAs) are considered promising vaccine candidates, for they are known to play important roles in erythrocyte invasion and are exposed to host immune system. Here we focused on a Plasmodium falciparum antigen, PfMSPDBL1 (encoded by PF10_0348 gene) that is a member of the MSP3 family and has both Duffy binding-like (DBL) domain and secreted polymorphic antigen associated with merozoites (SPAM) domain. Therefore, we aimed to characterize PfMSPDBL1 as a vaccine candidate. Recombinant full-length protein (rFL) of PfMSPDBL1 was synthesized by a wheat germ cell-free system, and rabbit antiserum was raised against rFL. We show that rabbit anti-PfMSPDBL1 antibodies inhibited erythrocyte invasion of wild type parasites in vitro in a dose dependent manner, and the specificity of inhibitory activity was confirmed using PfMSPDBL1 knockout parasites. Pre-incubation of the anti-PfMSPDBL1 antibodies with the recombinant SPAM domain had no effect on the inhibitory activity suggesting that antibodies to this region were not involved. In addition, antibodies to rFL were elicited by P. falciparum infection in malaria endemic area, suggesting the PfMSLDBL1 is immunogenic to humans. Our results suggest that PfMSPDBL1 is a novel blood-stage malaria vaccine candidate.     

Malaria vaccines: using models of immunity and functional genomics tools to accelerate the development of vaccines against Plasmodium falciparum

Naturally acquired immunity and immunity acquired after immunization with attenuated parasites indicate that a vaccine against malaria is feasible. Several obstacles have stymied malaria vaccine development, among them our poor understanding of protective immunity and technical difficulties for studying gene and protein expression in the Plasmodium falciparum parasite. Pregnancy malaria offers a model approach for vaccine development: recent findings have elucidated the basis for disease pathogenesis and protective immunity in this syndrome, and this understanding has focused the effort to identify the optimal antigens for a pregnancy malaria vaccine. In parallel, functional genomics tools are overcoming several of the obstacles for studying protein expression in the malaria parasite, vastly accelerating the pace for antigen discovery. Together, these conceptual and technological advances allow a rational approach to vaccine antigen selection, in which a finite number of antigens are selected from the entire genome by merit of the expression patterns and specific features. These candidate antigens are then subjected to detailed studies according to criteria established by the understanding of pathogenesis and protective immunity, to identify the optimal antigens for inclusion in subunit vaccines.     

A novel method for development of malaria vaccines using full-length cDNA libraries

We describe a novel method to screen malaria DNA vaccine candidates using a full-length cDNA library and a murine malaria infection model. For the development of effective malaria vaccines, much effort has been made with meager success. The completion of genome sequencing of Plasmodium falciparum has provided invaluable information for achieving this goal. We have been studying full-length cDNA libraries of malaria parasites as a part of genome analysis. Mice vaccinated with a DNA vaccine consisting of 2000 pooled clones showed significantly prolonged survival after challenge infection. In addition, spleen cells of vaccinated mice produced augmented levels of IL-2 and IFN-gamma when incubated with the crude parasite antigens, indicating that cellular immunity plays an important role in the protection. This approach will not only form the basis for development of malaria vaccines but will also be applicable to other parasites and pathogenic microorganisms.     

Identification of Plasmodium falciparum reticulocyte binding protein homologue 5-interacting protein,PfRipr, as a highly conserved blood-stage malaria vaccine candidate

Genetic variability in Plasmodium falciparum malaria parasites hampers current malaria vaccine development efforts. Here, we hypothesize that to address the impact of genetic variability on vaccine efficacy in clinical trials, conserved antigen targets should be selected to achieve robust host immunity across multiple falciparum strains. Therefore, suitable vaccine antigens should be assessed for levels of polymorphism and genetic diversity. Using a total of one hundred and two clinical isolates from a region of high malaria transmission in Uganda, we analyzed extent of polymorphism and genetic diversity in four recently reported novel blood-stage malaria vaccine candidate proteins: Rh5 interacting protein (PfRipr), GPI anchored micronemal antigen (PfGAMA), rhoptry-associated leucine zipper-like protein 1 (PfRALP1) and Duffy binding-like merozoite surface protein 1 (PfMSPDBL1). In addition, utilizing the wheat germ cell-free system, we expressed recombinant proteins for the four candidates based on P. falciparum laboratory strain 3D7 sequences, immunized rabbits to obtain specific antibodies (Abs) and performed functional growth inhibition assay (GIA). The GIA activity of the raised Abs was demonstrated using both homologous 3D7 and heterologous FVO strains in vitro. Both pfripr and pfralp1 are less polymorphic but the latter is comparatively more diverse, with varied number of regions having insertions and deletions, asparagine and 6-mer repeats in the coding sequences. Pfgama and pfmspdbl1 are polymorphic and genetically diverse among the isolates with antibodies against the 3D7-based recombinant PfGAMA and PfMSPDBL1 inhibiting merozoite invasion only in the 3D7 but not FVO strain. Moreover, although Abs against the 3D7-based recombinant PfRipr and PfRALP1 proteins potently inhibited merozoite invasion of both 3D7 and FVO, the GIA activity of anti-PfRipr was much higher than that of anti-PfRALP1. Thus, PfRipr is regarded as a promising blood-stage vaccine candidate for next-generation vaccines against P. falciparum.     

Vaccination against malaria: its plausibility and the present state of research

A vaccine for public health use against malaria is urgently required and is being actively researched into. The present review outlines the biology of malaria parasites and the immune response to them, with an emphasis on the worst of the human diseases, and considers the current analytical and molecular biological work on malaria parasite surfaces and antigens.     

A potent malaria vaccine based on adenovirus with dual modifications at Hexon and pVII

Adenovirus (Ad) is thought to be one of the most promising platforms for a malaria vaccine targeted against its liver stages, because of its ability to induce a strong T-cell response against a transgene. However, a further improvement of this platform is needed in order to elicit another arm of the immunity, i.e. humoral response, against malaria.In order to augment immunogenicity and protective efficacy of Ad-based malaria vaccine, we inserted B-cell, as well as CD4+ T-cell, epitopes of Plasmodium falciparum circumsporozoite protein (PfCSP) into the capsid protein, Hexon, and the core protein, VII (pVII), of Ad, respectively, in addition to the PfCSP transgene. Insertion of PfCSP-derived B cell epitope to Hexon significantly enhanced the epitope-specific antibody response compared to AdPfCSP, an Ad vaccine expressing only PfCSP transgene. PfCSP-derived CD4+ T-cell epitope insertion into pVII augmented not only PfCSP-specific CD4+ T-cell response but also anti-PfCSP antibody response. Finally, mice immunized with AdPfCSP having both Hexon and pVII modifications were more protected than AdPfCSP or Hexon-modified AdPfCSP against challenge with transgenic rodent malaria parasites expressing the PfCSP.Overall, this study has demonstrated that Hexon and pVII-modified AdPfCSP vaccine is a promising malaria vaccine which induces strong PfCSP-specific humoral, CD4+ T-cell, and CD8+ T-cell responses and protects against infection with transgenic malaria parasites expressing the PfCSP.     

Quantification of human complement factor H binding to asexual malaria blood stages by an enzyme-linked immunosorbent assay

The human complement system is the most effective defense mechanism of the human innate immune system. One major negative regulator of the alternative pathway in human blood is complement factor H (FH). It binds to autologous cells and thus, prevents complement attack against body-cells or tissues. Various pathogens are known to escape complement recognition by recruiting FH to provide protection against the host’s immune system. This immune evasion mechanism was recently qualitatively reported for asexual malaria blood stages. To indirectly evaluate the stage-specific potential of FH-receptor proteins as vaccine candidates, we quantified the FH molecules bound to the surface of different malaria blood stage parasites by Western blot and a commercially available FH-ELISA, which was originally designed to measure the FH concentration in human serum. Host-cell-free merozoites and intracellular mature schizont (here called segmenter) stages bind significantly more FH molecules than earlier parasite stages.