Role of T cell help and endoplasmic reticulum targeting in protective CTL response against influenza virus

We report on the induction of primary and long-term memory cytotoxic T lymphocyte (CTL) responses against the nucleoprotein of the influenza virus A/PR8/34 in mice immunized with plasmid DNA targeted to B lymphocytes in the spleen. We found that the magnitude of the CTL response and the size of the pool of memory CTL was greater when the CTL response was induced in presence of T cell help. Interestingly, immunization with a signal sequence-competent transgene was markedly superior to immunization with a transgene lacking the endoplasmic reticulum (ER) targeting sequence, in inducing CTL. We also found a correlation between in vivo protection from lethal virus challenge and (1) the availability of T cell help and (2) ER targeting. Immunization of dendritic cell-deficient mice suggests that B lymphocytes function as antigen-presenting cells in this model of immunization. Collectively, the results suggest that somatic transgene immunization is a conceptually new approach to induce effective anti-viral CTL responses and to assess the parameters critical for long-lasting and protective CTL responses in vivo.     

多CTL表位DNA疫苗诱导特异性CTL应答的研究

目的:构建多CTL表位DNA疫苗诱导特异性CTL应答。方法:将编码两个HCVCTL表位(H-2d)的基因序列插入真核表达载体pcDNA3.1中,构建多CTL表位DNA疫苗。用其免疫BALB/c小鼠后,以经不同CTL抗原肽冲击的P815细胞(H-2d)作为靶细胞,进行CTL杀伤试验。结果:多CTL表位DNA疫苗可诱导机体产生针对其编码的两种HCVCTL表位的特异性CTL免疫应答,且总的特异性CTL杀伤效应增强。结论:通过天然侧翼氨基酸相连的多个CTL表位为编码序列构建的多CTL表位DNA疫苗,不但能诱导机体产生针对各个CTL表位的特异性CTL应答,而且各特异性CTL应答的联合作用可显著增强总的CTL杀伤效应。     

EB病毒潜伏膜蛋白2 DNA疫苗的构建及其初步免疫效果观察

目的：以EB病毒潜伏膜蛋白2（latent membrane protein 2,LMP2)为靶基因,构建EBV－LMP2的侯选DNA疫苗,并初步探讨其在小鼠体内诱导特异性细胞毒方面的作用,为研制鼻咽癌（nasopharyngeal carcinoma,NPC)等EB病毒相关肿瘤的治疗性疫苗提供有益资料。方法：将EB病毒LMP2全cDNA片段克隆至含CMV早期启动子的真核表达载体pCDNAⅢ,构建CMV启动子EB病毒LMP2DNA疫苗,在体外将重组质粒转染COS细胞,以RT－PCR和间接免疫荧光法检测重组质粒在转染的COS细胞中的转录和表达,采用50μg,100μg,200μg3种质粒剂量进行初步的小鼠后可诱发机体产生会对LMP2蛋白的特异性体液免疫和细胞免疫,50μg,100μg,200μg 3种免疫剂量产生的抗体水平差异不大。在免疫接种6周后,重组质粒免疫的小鼠产生针对LMP2的特异性CTL均明显高于空载体免疫小鼠,3种剂量的CTL结果显示：在100μg,200μg免疫组,小鼠诱导产生的CTL水平要略高于50μg免疫组。结论：EB病毒重组质粒LMP2免疫小鼠可以诱发小鼠产生特异的体液和细胞免疫应答,这些结果为研制鼻咽癌DNA疫苗提供有益的资料。     

Peptide-specific CTL induction in HBV-seropositive PBMC by stimulation with peptides in vitro: novel epitopes identified from chronic carriers

Cytotoxic T lymphocytes (CTL) recognize and destroy virus-infected cells, and it has been established that epitope-based peptides could induce such CTL in vivo as well as in vitro. In this study attempts were made to define the epitopes that are recognized by the CTL, and thus a series of 9- to 10-mer peptides derived from the amino acid sequences of hepatitis B virus (HBV) proteins were synthesized on the basis of the previously described HLA-A2 peptide binding motif. The binding assay of the synthetic peptides using transporter-associated with antigen processing (TAP)-deficient human cell line, T2, showed that eight out of 11 peptides tested enhanced the expression of HLA-A2 molecules on the T2 cell surface. Some of these peptides triggered activation of CTL in peripheral blood mononuclear cells of HBV-seropositive chronic carriers. The activated CTL in turn recognized and killed the T2 cells pulsed with the same peptides. This study shows that novel HLA-A2-restricted epitopes exist in the natural repertoire of immunity against HBV. These findings can be useful in developing peptide-based therapeutics against viral infections.     

In vivo electroporation improves therapeutic potency of a DNA vaccine targeting hepadnaviral proteins

This preclinical study investigated the therapeutic efficacy of electroporation (EP)-based delivery of plasmid DNA (pDNA) encoding viral proteins (envelope, core) and IFN-γ in the duck model of chronic hepatitis B virus (DHBV) infection. Importantly, only DNA EP-therapy resulted in a significant decrease in mean viremia titers and in intrahepatic covalently closed circular DNA (cccDNA) levels in chronic DHBV-carrier animals, compared with standard needle pDNA injection (SI). In addition, DNA EP-therapy stimulated in all virus-carriers a humoral response to DHBV preS protein, recognizing a broader range of major antigenic regions, including neutralizing epitopes, compared with SI. DNA EP-therapy led also to significant higher intrahepatic IFN-γ RNA levels in DHBV-carriers compared to other groups, in the absence of adverse effects. We provide the first evidence on DNA EP-therapy benefit in terms of hepadnaviral infection clearance and break of immune tolerance in virus-carriers, supporting its clinical application for chronic hepatitis B.     

DNA疫苗诱导健康小鼠细胞免疫及HBV转基因小鼠抗-HBs产生

目的 :在HBVDNA疫苗成功地诱导健康小鼠体液免疫应答的基础上 ,探讨其作为抗 HBV治疗的可行性及作用机理。方法 :应用基因重组技术 ,构建编码HBV中蛋白 (preS2 +S)及人白细胞介素融合蛋白基因的真核表达质粒pS2 .S及pFP ,继经肌注免疫健康Balb C及HBV转基因 (Tg)小鼠并观察健康小鼠细胞免疫应答及HBVTg小鼠HBsAg的血清转换。结果 :1 体外HBsAg对DNA疫苗免疫后的T细胞的刺激呈浓度相关 ,HBsAg 30 μg ml时刺激pS2 .S免疫小鼠脾细胞增殖指数(5 6± 0 9)明显较pcDNA3 1组 (2 0± 0 5 )高。细胞培养上清液细胞因子水平检测结果 :免疫实验组IL 2及IFN γ的分泌水平明显较对照组高 ,而IL 4水平于各组影响不明显。 2 pS2 .S免疫小鼠局部引流淋巴结DCs诱导HBsAg致敏的T 细胞增殖指数(4 2 0 )较pcDNA3.1组 (2 5 5高 )。 3 高剂量的pS2 .S组与联合pFP组各有一只Tg小鼠分别于 2、4w开始发生HBsAg血清转换 ,且其抗体水平随时间而增长。结论 :结果表明HBVDNA疫苗能有效诱导HBsAg特异性的细胞免疫应答 ;HBV Tg小鼠初步实验结果为治疗型HBVDNA疫苗的深入研制提供了实验依据。     

IL-12对结构优化的HBV核心抗原DNA疫苗诱导免疫应答的影响

目的 探讨IL-12对一种结构优化的HBV核心抗原(HBcAg)DNA疫苗免疫效果的影响。方法 将小鼠IL-12基因插入结构优化的DKA疫苗pST-HBc，构成pST-HBc/IL12，将pST-HBc／IL12转染COS7细胞，ELISA检测培养上清中的HBcAg和小鼠IL-12。分别将pST-HBc／IL12和pST-HBc肌肉注射接种BALB／c小鼠，检测小鼠的体液和细胞免疫应答。结果 ELISA检测到培养上清液中的HBcAg和小鼠IL-12，pST-HBc／IL12诱导的抗-HBc总IgG阳转率和抗体水平不及pST-HBc，但其诱导的脾细胞增殖反应和细胞毒性T淋巴细胞反应均强于pST-HBc。结论 IL-12可进一步增强这种HBcAgDNA疫苗诱导的细胞免疫应答。     

Peptide immunization in humans: a combined CD8+/CD4+ T cell-targeted vaccine restimulates the memory CD4 T cell response but fails to induce cytotoxic T lymphocytes (CTL)

Immunization with short antigenic peptides represents a potential strategy to induce peptide-specific CTL in vivo. In this study, a synthetic vaccine consisting of an HIV-derived, HLA-A2.1-binding CTL epitope and a tetanus toxin-derived T helper epitope was evaluated for its capacity to induce peptide-specific CTL in humans. Thirteen volunteers were immunized and boosted twice with 100 μg of the CTL epitope plus 300 μg of the T helper peptide (p30). Peripheral blood mononuclear cells (PBMC) were regularly analysed for cytotoxic and proliferative responses before, between and after the immunizations, and the serum was tested for anti-peptide antibodies. No unequivocal induction of HIV peptide-specific CTL in any of the volunteers was observed. However, a wide pattern of mild and transient side reactions was observed, ranging from local redness at the injection site to generalized exanthema, myalgias, arthralgias and fever. The side-effects were related to the T helper epitope, as they were similar to the side-effects experienced after tetanus immunization, correlated to the magnitude of the p30-specific in vitro proliferative response, and occurred only if p30 was co-injected. No antibodies against the HIV-derived peptides nor against p30 were detectable in the serum after repeated immunizations. The data suggest that the CTL peptide, at the concentration used in this study, failed to induce a cytotoxic immune response in vivo, although the T helper peptide seems to be capable of restimulating the specific memory T cells.     

小鼠HCV皮下移植瘤的建立及DNA 疫苗的治疗作用

目的　建立小鼠丙型肝炎病毒（HCV）皮下移植瘤,并以其为HCV感染动物模型,观察HCV核心(C)基因DNA疫苗（pcDNA-HCV-C）在体内对HCV感染的治疗作用。方法　将pcDNA-HCV-C用脂质体（LipofectAMINE）法转染BALB/c小鼠骨髓瘤Sp2/0（H-2     

Enhanced magnitude and breadth of neutralizing humoral response to a DNA vaccine targeting the DHBV envelope protein delivered by in vivo electroporation

We explored in the duck hepatitis B virus (DHBV) model the impact of electroporation (EP)-mediated DNA vaccine delivery on the neutralizing humoral response to viral preS/S large envelope protein. EP enhanced the kinetics and magnitude of anti-preS response compared to the standard needle DNA injection (SI). Importantly, EP dramatically enhanced the neutralizing potency of the humoral response, since antibodies induced by low DNA dose (10 μg) were able to highly neutralize DHBV and to recognize ten antigenic regions, including four neutralization epitopes. Whereas, SI-induced antibodies by the same low DNA dose were not neutralizing and the epitope pattern was extremely narrow, since it was limited to only one epitope. Thus, EP-based delivery was able to improve the dose efficiency of DNA vaccine and to maintain a highly neutralizing, multi-specific B-cell response, suggesting that it may be an effective approach for chronic hepatitis B therapy at clinically feasible DNA dose.     

MUC1基因疫苗诱导小鼠特异性CTL和体液免疫应答

目的 :观察MUC1基因疫苗诱导小鼠特异性杀伤性T细胞及体液免疫应答的作用。方法 :采用股四头肌肌肉注射 ,将构建的MUC1基因疫苗pcDNA3.1 MUC1免疫雌性BALB/c小鼠 ,每次间隔 3wk ,共 3次。最后 1次免疫后第 3周 ,接种表达MUC1的EMT6乳腺癌细胞进行免疫保护实验。用 4h51Cr释放法检测小鼠脾细胞特异性CTL杀伤活性 ;免疫组化染色法检测小鼠血清特异性抗体的水平。结果 :在效靶比为 10 0∶1、5 0∶1、2 5∶1、12 .5∶1时 ,MUC1基因疫苗免疫组特异性CTL对EMT6靶细胞杀伤活性分别为 5 4 .1%、39.8%、2 6 .4 %和2 0 .1% ,对照组分别为 13.2 %、10 .0 %、8.2 %、7.2 %和 11.7%、9.8%、7.7%、7.0 % ,前者与后二者差异显著 (P <0 .0 1)。免疫组化染色检测显示 ,人乳腺癌组织MUC1呈染色阳性 ;MUC1基因疫苗免疫组仅见 4 0 % (4/ 10 )的小鼠有肿瘤形成 ,而 pcDNA3.1对照组和生理盐水阴性对照组 10 0 %可见肿瘤形成、生长 ,表明MUC1基因疫苗免疫组小鼠具有一定的免疫保护作用。结论 :MUC1基因疫苗可诱导小鼠产生特异性CTL及体液免疫应答 ,对小鼠体内荷瘤可能具有一定的预防作用     

免疫途径及载体对乙肝病毒DNA疫苗免疫效果影响的研究

目的探讨ＤＮＡ载体结构及接种途径对ＤＮＡ疫苗免疫效果的影响。方法分别构建插入ＨＢＶ表面抗原编码基因的表达载体ｐｃＤＮＡ１．１／ＳＡ（无抗性基因）和ｐｃＤＮＡＩ／Ａｍｐ／ＳＡ（含氨苄青霉素抗性基因）,肌注小鼠后比较其诱生特异性免疫应答的能力;同时比较不同接种途径（肌内、皮内、皮肤划痕）及ＣｐＧ免疫刺激元件（ＩＳＳ）对ＤＮＡ疫苗诱生免疫效果的影响。结果ｐｃＤＮＡＩ／Ａｍｐ／ＳＡ的免疫效果优于ｐｃＤＮＡ１．１／ＳＡ。ｐｃＤＮＡ１．１／ＳＡ的免疫效果可被ＩＳＳ增强,而ｐｃＤＮＡＩ／Ａｍｐ／ＳＡ诱生特异性免疫应答的能力则可被ＩＳＳ抑制;诱生免疫应答的能力以肌内注射最强,皮内注射免疫其次,皮下划痕法较弱。结论不同ＨＢｓＡｇ表达载体诱生免疫应答的能力不尽相同;ＣｐＧ免疫刺激元件在决定ＤＮＡ疫苗免疫原性中起重要作用,可增强不含相应结构ＤＮＡ疫苗的免疫效果;皮内注射可诱发与肌内接种相似的免疫应答,是一种简便、有效的免疫接种途径     

乙肝病毒核心抗原DNA疫苗诱导小鼠抗原特异性CD8+T细胞动态变化和动态分布

目的：研究乙肝病毒核心抗原(HBcAg)DNA疫苗诱导的细胞免疫应答。方法：用表达乙肝病毒核心抗原N端144个氨基酸的重组质粒DNA(简称pHBc144)100ug免疫C57BL／6小鼠，用细胞内细胞因子染色技术检测小鼠体内抗原特异性CD8^ T细胞的动态变化。结果：pHBc144免疫后抗原特异性CD8^ T细胞逐渐增多，在初次免疫的第14天出现第一个免疫应答高峰，此后抗原特异性CD8^ T细胞数量逐渐下降进入免疫记忆期并在1年内维持在稳定水平。加强免疫后在第10天抗原特异性CD8^ T细胞数量达到高峰，约是初次免疫应答高峰的2倍，此后抗原特异性CD8^ T细胞数量逐渐下降，但下降的速度比初次免疫应答减缓。结论：pHBc144DNA疫苗可诱导有效的细胞免疫应答。     

A sequence pattern for peptides presented to cytotoxic T lymphocytes by HLA B8 revealed by analysis of epitopes and eluted peptides

HLA B8-restricted cytotoxic T lymphocytes (CTL) specific for influenza A virus were generated and shown to recognize the nucleoprotein (NP). The dominant epitope was mapped using recombinant vaccinia viruses that expressed fragments of the NP and then synthetic peptides baseds on the NP amino acid sequence. The peptide 380-393 was first identified and further refined; it was shown that the glutamic acid at position 380 was essential for recognition by CTL and that the nonamer 380-388 was the optimum peptide. Six HLA B8-positive influenza immune donors that we have tested respond to this peptide as part of their influenza-specific CTL response. The amino acid sequence of the peptide epitope was compared to six other known virus peptides known to be restricted by HLA B8 and a sequence homology was identified, which predicted nonamer and octamer epitope sequences. Probable anchor residues were identified at peptide residues 3 (lysine/arginine), 5 (lysine/arginine) and 9 (leucine/isoleucine). Support for this pattern came from sequencing peptides eluted from purified HLA B8 molecules, where lysines were predominant at positions 3 and 5. One of the predicted epitope peptides was made and shown to be recognized by specific CTL. These and the two others were shown to compete with NP 380-388 for binding to HLA B8. A model was made of the HLA B8 molecule and negatively charged pockets predicted, which could accomodate the positively charged side chains of the peptide anchor residues.     

双重表达乙肝病毒前S2抗原的重组质粒的疫苗效应

目的：乙肝病毒（HBV）的前S2抗原具有比S抗原更强的免疫原性，可以更有效地诱生特异性免疫应答。文中构建含有前S2抗原编码基因的3种重组质粒，观察接种后诱生特异性体液免疫应答的情况。方法：采用PCR技术扩增HBV的S2-S和S1-S2-S基因；同时串联拼接产生S2-S-S2片段。继而构建重组表达质粒pcDNA3．1／S2S、pcDNA3．1／S1S2S和pcDNA3．1／S2SS2。后者意在表达S抗原的同时，双重表达前S2抗原。然后将上述3种质粒分别以100μg肌肉接种BALB／c小鼠，于2、4周后各加强1次。初次接种后3、5、8和12周，分别采血检测小鼠的前S2抗体和抗-HBs。结果：初次接种后3周，S2SS2组小鼠血清的前S2抗体检出率为12．5％，低于S1S2S组（25％）和S2S组（37．5％）；但5周时则达到87．5％，并持续到12周，优于S1S2S组和S2S组；并且S2SS2组的前S2抗体滴度达到1：2000，高于S2S组（1：500）和S1S2S组（1：50）。不过，S2SS2组同期的抗-HBs检出率和抗-HBs滴度则低于S1S2S组和S2S组。结论：重组质粒pcDNA3．1／S2S-S2以串联拼接方式双重表达前S2抗原，能够诱生较高水平的特异性前S2抗体，但其诱生抗HBs的能力却明显降低，这是在设计改造基因疫苗时需要考虑的一个重要问题。     

乙型肝炎病毒多表位抗原DNA疫苗的免疫原性

目的 :探讨HBV复合多表位DNA疫苗诱导体液及细胞免疫的可行性。方法 :将HBV多表位抗原基因BPT克隆到真核表达载体pcDNA3.1中 ,构建重组真核表达载体pcDNA3.1/BPT。将其通过肌肉注射免疫BALB/c小鼠 ,用间接免疫ELISA法、CTL杀伤功能检测和淋巴细胞增殖试验 ,检测特异性体液免疫和细胞免疫的水平 ,并观察其对免疫小鼠的毒副作用。结果 :用重组质粒pcDNA3.1/BPT免疫BALB/c小鼠后 ,在效靶比为 10 0∶1时 ,可诱导显著地特异性CTL应答 (P <0 .0 5 )。ELISA检测免疫小鼠血清特异性IgG的水平明显升高 (P <0 .0 5 )。在BPT基因原核表达蛋白的刺激下 ,免疫小鼠脾淋巴细胞增殖显著 (P <0 .0 5 )。RT PCR分析表明 ,IL 12mRNA的水平亦明显升高。结论 :HBV多表位基因疫苗可诱发特异性免疫应答 ,为预防、治疗性HBV疫苗的研制提供了一定的实验依据     

B7-2表达质粒对HBV DNA疫苗诱导的特异性免疫应答的影响

目的：探讨B7－2分子是否能够增强乙型肝炎病毒（HBV）DNA疫苗诱导的特异性免疫应答。方法：将B7－2表达质粒与HBV DNA疫苗共接种于小鼠腓肠肌内，检测细胞毒性T淋巴细胞（CTL）活性，迟发性超敏反应（DTH）及抗－HBs滴度。结果：B7－2表达质粒与HBV DNA疫苗共接种组的DTH反应和CTL活性，明显强于单独接种HBV DNA疫苗组（P＜0．01）。两组的抗－HBs滴度差异无显著性（P＞0．05）。结论：B7－2表达质粒与HBV DNA疫苗共接种可显著增强抗－HBV特异性细胞免疫应答（CMI）。     

乙型肝炎病毒DNA疫苗电转加强含S-PreS1颗粒的蛋白疫苗在小鼠中免疫效果的研究

目的探索新型有效的HBV治疗性疫苗研制的策略。方法构建含S与PreS1融合基因的HBVDNA疫苗,采用两次蛋白疫苗（含不同佐剂）肌内注射初免,一次DNA疫苗皮内电转免疫加强的联合免疫方式,在小鼠中分析比较了各疫苗所引起的体液与细胞免疫应答。结果HBVDNA疫苗皮内注射加电转可明显增强表面抗原（s）特异的细胞免疫应答（IFN-γ ELISpot分析）及PreS1特异性抗体水平,并以蛋白疫苗加铝佐剂初免组细胞免疫增强效果最明显。结论HBSS1 DNA疫苗结合皮内注射＋电转方式可明显加强含S-PreS1颗粒的蛋白疫苗在小鼠中免疫效果,明显高于蛋白疫苗单独应用。这些研究结果为新型HBV治疗性疫苗的研制与应用提供了依据。     

表达丙型肝炎病毒NS3和Core融合蛋白基因的DNA疫苗免疫方案优化

目的 本研究旨在构建一种包含丙型肝炎病毒(HCV)保守区基因的新型DNA疫苗,并在小鼠模型中使用电转技术优化其免疫原性.方法 首先,我们构建了包含HCV非结构蛋白NS3和核心蛋白Core部分基因序列的DNA疫苗,并证实了其表达;然后采用不同的体内电转方式于第0、4周分别免疫BALB/c小鼠,比较分析不同免疫方案的体液免疫(特异性IgG与抗体亚类)与细胞免疫应答(IFN-γ ELISPOT)的效果.结果 使用电转技术可显著增强新型DNA疫苗免疫原性,采用皮内注射加卡钳电极电转的方式产生最强NS3特异性T细胞免疫反应.结论 包含HCV保守区基因的新型DNA疫苗可通过优化电转技术增强免疫应答效果.这为我们下一步优化HCV DNA疫苗的免疫方案提供了依据.     

颗粒性HBV多CTL表位基因诱导BALB/c小鼠的免疫应答研究

目的：研究含HBV多CTL表位的杂合HBc基因免疫BALB/c小鼠所诱导的免疫应答.方法：构建以HBV多CTL表位取代MIR区基因的杂合HBc基因疫苗（pHBcMep）并以肌肉注射方式免疫BALB/c小鼠,ELISA、流式细胞术、LDH释放法等分别检测血清特异性抗体与淋巴细胞分泌的IFN-γ水平、CD4^＋/CD8^＋T细胞比例变化及特异性CTLs活性等免疫应答指标.结果：颗粒性杂合HBc基因疫苗pHBcMep免疫BALB/c小鼠诱导明显抗体应答,末次免疫后2周,特异性抗preS2抗体阳性率达100%（12/12）,最高效价1∶1 000,同时诱导淋巴细胞分泌IFN-γ能力增强和刺激CTLs活化,其杀伤活性达16 IU30,CD4^＋/CD8^＋T细胞比例明显升高,且诱导明显回忆反应.结论：颗粒性HBV多CTL表位基因疫苗pHBcMep具有良好免疫原性,能迅速诱导高活性体液和细胞免疫应答及回忆反应.