日本血吸虫Sj Cyclophilin B基因的克隆、表达及免疫保护效果分析

本研究克隆和表达了日本血吸虫Cyclophilin B(Sj CyPB)编码基因的cDNA,分析其在日本血吸虫不同发育阶段虫体的表达情况,评估该重组抗原在小鼠体内诱导的抗血吸虫免疫保护效果。本研究以日本血吸虫童虫cDNA为模板,RT-PCR扩增其基因全长cDNA,提交序列到NCBI,登录号为GQ403665。荧光实时定量PCR分析该基因在日本血吸虫不同发育阶段虫体的表达情况,构建重组表达质粒,表达纯化重组蛋白。利用Western blotting检测重组蛋白的抗原性。以重组抗原免疫小鼠,评估其对小鼠诱导的免疫保护效果。结果表明,RT-PCR获得了Sj CyPB编码基因的全长cDNA,其开放阅读框为672bp。经分析确定其为CyPs家族中的CyPB基因,命名为Sj CyPB。荧光实时定量PCR分析表明,该基因在18d童虫期表达量最高,32d次之。构建了重组表达质粒pGEX-6P-1-SjCyPB,并在大肠杆菌中成功表达,表达产物分子量为49.5kDa。Western blotting试验显示该重组蛋白具有良好的抗原性,在小鼠免疫试验中,与空白对照组比较,免疫组小鼠获得31.5%的减虫率和41.01%的肝脏减卵率。本研究获得了日本血吸虫童虫期高表达的Sj CyPB基因的全长cDNA,成功构建了Sj CyPB原核重组表达质粒,并在大肠杆菌中成功表达,证实该重组抗原在小鼠体内诱导产生了部分免疫保护效果。     

Identification of immunodominant Th1-type T cell epitopes from Schistosoma japonicum 28 kDa glutathione-S-transferase, a vaccine candidate

Th1-type cytokines produced by the stimulation of Th 1-type epitopes derived from defined schistosome-associated antigens are correlated with the development of resistance to the parasite infection. Schistosoma mansoni 28 kDa glutathione-S-transferase （Sm28GST）, a major detoxification enzyme, has been recognized as a vaccine candidate and a phase II clinical trial has been carried out. Sheep immunized with recombinant Schistosoma japonicum 28GST （Sj28GST） have shown immune protection against the parasite infection. In the present study, six candidate peptides （P1, P2, P3, P4, P7 and P8） from Sj28GST were predicted, using software, to be T cell epitopes, and peptides P5 and P6 were designed by extending five amino acids at the N-terminal and C-terminal of P1, respectively. The peptide 190-211 aa in Sj28GST corresponding to the Th1-type epitope （190-211 aa） identified from Sm28GST was selected and named P9. The nine candidate peptides were synthesized or produced as the fusion protein with thioredoxin in the pET32c（＋）/BL21（DE3） system. Their capacity to induce a Th1-type response in vitro was measured using lymphocyte proliferation, cytokine detection experiments and flow cytometry. The results showed that P6 （73-86 aa） generated the strongest stimulation effect on T cells among the nine candidate peptides, and drove the highest level of IFN-γ, and IL-2. Therefore, P6 is a functional Thl-type T cell epitope that is different from that in Sm28GST, and will be useful for the development of effective vaccines which can trigger acquired immunity against S. japonicum. Moreover, our strategy of identifying the Thl-type epitope by a combination of software prediction and experimental confirmation provides a convenient and cost-saving alternative approach to previous methods.     

利用基因免疫进行日本血吸虫Sj22蛋白抗体制备的研究

应用基因免疫方法制备日本血吸虫Sj22蛋白的抗体,并研究CpG佐剂和蛋白加强策略在增强基因免疫效果中的作用。采用肌肉注射的方法免疫小鼠,实验动物分为四组：A组注射pVAX1-sj22质粒100μg /只;B组注射pVAX1-sj22质粒50μg /只,同时注射CpG佐剂20μg /只;C、D组注射pcDNA3.1-sj22质粒100μg /只。分别在0,3,6周进行免疫,第9周A、B、C组用30μg重组sj22蛋白加强免疫,D组则用pcDNA3.1-sj22质粒100μg加强免疫。第0,9,10周割尾采血,使用ELISA方法进行抗体效价测定,Western blot验证抗体的特异性。结果表明：使用基因免疫的方法获得了针对Sj22的特异性抗血清,CpG佐剂能够有效降低质粒用量,基因免疫-蛋白加强的策略使得抗体的滴度提高了40～1280倍。     

Transport of glutathione transferase-fold structured proteins into living cells

Glutathione transferases are a family of enzymes that are traditionally known to contribute to the phase II class of detoxification reactions. However, a novel property of the Schistosoma japonicum glutathione transferase (Sj.GST26) involves its translocation from the external medium into a variety of different cell types. Here we explore the efficiency and mechanism of cell entry for this class of protein. Using flow cytometry and confocal microscopy, we have examined the internalisation of Sj.GST26 into live cells under a variety of conditions designed to shed light on the mode of cellular uptake. Our results show that Sj.GST26 can effectively enter cells through an energy-dependent event involving endocytosis. More specifically, Sj.GST26 was found to colocalise with transferrin within the cell indicating that the endocytosis process involves clathrin-coated pits. A comprehensive study into the cellular internalisation of proteins from other classes within the GST structural superfamily has also been conducted. These experiments suggest that the ‘GST-fold’ structural motif influences cellular uptake, which presents a novel glimpse into an unknown aspect of GST function.     

Schistosoma japonicum: The design and experimental evaluation of a multivalent DNA vaccine

The aim of this study was to construct and evaluate the immunity efficacy of the DNA multivalent vaccine pVIVO₂SjFABP-23. The vaccine was constructed and produced as follows. Forty BALB/c mice were divided into four groups designated pVIVO₂, pVIVO₂Sj23, pVIVO₂SjFABP and pVIVO₂SjFABP-23. Each mouse was immunized with 100 μg of the corresponding plasmid DNA by intramuscular injection. 28 days post-vaccination, the mice were challenged with S. japonicum cercariae, and the worm and egg burdens were determined 42 days post-challenge. Serum samples were collected from all the mice before and after vaccination and at the end of the experiment, and used for antibody detection. The IFN-γ and IL-4 levels were quantified in the supernatants of specifically stimulated spleen cells. The number of worms was reduced by 52%, 40% and 42% in mice respectively immunized with pVIVO₂SjFABP-23, pVIVO₂Sj23 or pVIVO₂SjFABP. A respective 61%, 38% and 39% egg reduction was determined relative to those mice that only received the empty pVIVO2 plasmid. pVIVO₂SjFABP-23 immunization increased IgG levels against SWAP and SEA. Increased IFN-γ levels were detected in the supernatant of specific stimulated spleen cells from mice immunized with the 3 different constructs. The multivalent DNA vaccine developed induced higher levels of protection than the two monovalent tested vaccines.     

Characterization of the electrophile binding site and substrate binding mode of the 26-kDa glutathione S-transferase from Schistosoma japonicum

The 26-kDa glutathione S-transferase from Schistosoma japonicum (Sj26GST), a helminth worm that causes schistosomiasis, catalyzes the conjugation of glutathione with toxic secondary products of membrane lipid peroxidation. Crystal structures of Sj26GST in complex with glutathione sulfonate (Sj26GSTSLF), S-hexyl glutathione (Sj26GSTHEX), and S-2-iodobenzyl glutathione (Sj26GSTIBZ) allow characterization of the electrophile binding site (H site) of Sj26GST. The S-hexyl and S-2-iodobenzyl moieties of these product analogs bind in a pocket defined by side-chains from the beta1-alpha1 loop (Tyr7, Trp8, Ile10, Gly12, Leu13), helix alpha4 (Arg103, Tyr104, Ser107, Tyr111), and the C-terminal coil (Gln204, Gly205, Trp206, Gln207). Changes in the Ser107 and Gln204 dihedral angles make the H site more hydrophobic in the Sj26GSTHEX complex relative to the ligand-free structure. These structures, together with docking studies, indicate a possible binding mode of Sj26GST to its physiologic substrates 4-hydroxynon-2-enal (4HNE), trans-non-2-enal (NE), and ethacrynic acid (EA). In this binding mode, hydrogen bonds of Tyr111 and Gln207 to the carbonyl oxygen atoms of 4HNE, NE, and EA could orient the substrates and enhance their electrophilicity to promote conjugation with glutathione.     

Rapid and significant induction of TRAIL-mediated type II cells in apoptosis of primary salivary epithelial cells in primary Sjögren’s syndrome

Expressions of the effector molecules of Fas-mediated apoptosis in primary cultured salivary gland epithelial cells (SGEC) of primary Sjögren’s syndrome (pSS) remain to be clarified. We focused on Fas-mediated caspase cleavage compared to tumor necrosis factor-related apoptosis inducing ligand (TRAIL)-mediated apoptosis. Induction of apoptosis was performed by anti-Fas antibody coupled with PI3K inhibitor, or TRAIL. Activation of caspases, cytochrome C, and apoptotic protease activating factor-1 (Apaf-1) was determined by western blotting or immunofluorescence observed by confocal microscopy. Fas-mediated apoptosis and activation of caspase 3/8 were induced in the presence of LY294002. TRAIL-induced apoptosis in SGEC, which was stronger than that induced by anti-Fas antibody. TRAIL-induced caspase 9 cleavage accompanied by activation of cytochrome C and Apaf-1 were not mediated by anti-Fas antibody. Our results suggest that death receptor-dependent apoptosis in primary cultured SGEC is regulated by the engagement of type II cells in pSS.     

以中枢神经系统受累为首发表现的干燥综合征1例并文献复习

目的:提高对干燥综合征中枢神经系统损害的认识,了解其特点及治疗。方法:报告1例以中枢神经系统受累为首发表现的干燥综合征病例,并对相关文献进行复习。结果:此例患者以脊髓病变为首发症状,长期口干、眼干,查体及实验室等相关检查诊断干燥综合征明确。结论:干燥综合征可存在中枢神经系统损害,其中脊髓病变较常见,应注意完善影像学及脑脊液检查,并与系统性红斑狼疮等结缔组织病相鉴别。     

日本血吸虫三价DNA疫苗pVIVO2 SjFABP/Sj26.SjGAPDH的构建及其免疫保护作用评价

目的:构建含有日本血吸虫中国大陆株脂肪酸结合蛋白(SjFABP),3-磷酸甘油醛脱氢酶(SjGAPDH),26kDa谷胱甘肽S转移酶(Sj26)的三价DNA疫苗,并通过药理实验评价其抗血吸虫感染的免疫保护作用。 方法:  以血吸虫成虫RNA为模板制备cDNA第一链,RT-PCR扩增得到抗原基因片段,再通过重组PCR技术,将Sj26和SjGAPDH融合为Sj26.SjGAPDH基因。将SjFABP和Sj26.SjGAPDH分别克隆入pVIVO2的mcs1和mcs2,获得重组质粒pVIVO2-SjFABP/Sj26.SjGAPDH。瞬时转染MCF-7细胞,通过逆转录PCR（RT-PCR）检测抗原基因在mRNA水平的表达,通过间接荧光免疫（IIF）检测抗原基因在小鼠体内抗原水平表达,验证了DNA疫苗的有效性;并免疫小鼠后进行免疫保护性初步试验。结果:  经过酶切、测序及体内外表达验证,该三价DNA疫苗pVIVO2-SjFABP/Sj26.SjGAPDH构建成功;该三价DNA疫苗在小鼠抗血吸虫感染中诱发减虫率和减卵率达到58.6%和59.8%。结论:  该三价DNA疫苗组具有比单价和双价DNA疫苗组更加良好的免疫保护作用,为日本血吸虫DNA疫苗的研制奠定了基础。     

Expression, immunolocalization and serodiagnostic value of a myophilin-like protein from Schistosoma japonicum

The cDNA of a Schistosoma japonicum myophilin-like protein was cloned, sequenced, and expressed in Escherichia coli as a recombined protein (rSj myophilin-like protein), and the protein was purified by affinity chromatography. The deduced amino acid sequences of the Sj myophilin-like protein showed significant homology to myophilin, calponin, Np22 and Mp20. Northern blot and RT-PCR analyzes revealed expression of the Sj myophilin-like protein mRNA in eggs, sporocysts, cercariae, hepatic schistosomula and adult worms. Confocal fluorescence microscopy localized the native protein to the muscle of the adult worm. In schistosome-infected rabbits, the rSj myophilin-like protein antibody level, assessed by ELISA, was elevated after infection but was reduced after praziquantel treatment. In humans, the myophilin-like protein antibody level was evaluated by ELISA in sera from 33 non-infected humans and 61 schistosomiasis patients; the results showed a highly significant difference between the two groups with a sensitivity of 57.4%. Taken together, the myophilin-like protein may prove useful for monitoring the therapeutic effect of praziquantel rather than in serodiagnosis of schistosomiasis.