DNA疫苗及其免疫途径的研究进展

<正>DNA疫苗(DNA vaccine)又称为核酸疫苗、基因疫苗,是指将含有编码某种抗原蛋白基因序列的质粒载体作为疫苗,采用某种方法直接导入动物细胞内,然后通过宿主细胞的转录翻译系统合成抗原蛋白,诱导宿主产生对该抗原蛋白的免疫应答,从而使被接种动物获得相应的免疫保护,以达     

口服鼠疫F1-V重组融合基因DNA活菌疫苗的构建及免疫原性研究

目的 构建携带鼠疫耶尔森菌F1-V融合基因的重组减毒沙门菌苗,口服免疫Balb/c小鼠检测其免疫原性,为口服鼠疫活载体DNA疫苗研究打下基础.方法 将F1-V融合基因克隆到真核表达载体asd-pVAX1,进一步依次将重组质粒转化减毒沙门菌X3730、X4550得到重组沙门菌X4550(asd-pVAX1/F1-V),提取重组质粒转染COS-7细胞并做免疫组化和Western-blot检测F1-V融合蛋白在细胞中的表达.以1×109CFU/只的剂量3次口服免疫Balb/c小鼠,ELISA方法检测血清中抗体水平.结果 构建的重组减毒沙门菌转染COS-7细胞后,免疫组化和Western-blot试验证明F1-V融合蛋白在细胞中得到了瞬时表达,ELISA检测到免疫小鼠血清有特异性抗体IgG产生.结论 构建的重组沙门菌能运送DNA疫苗到体内并成功释放质粒刺激机体产生特异性免疫应答,为口服鼠疫活载体DNA疫苗的黏膜免疫研究打下了基础.     

携带tPA信号肽序列HuZP3核心抗原核酸疫苗质粒的构建与体外瞬时表达

目的:构建含有组织型纤溶酶原激活剂(tPA)信号肽的人卵透明带3(HuZP3)蛋白核心抗原核酸疫苗质粒并进行体外瞬时表达。方法:将HuZP3基因用PCR方法扩增并分别引入限制性内切酶酶切位点,然后克隆入pIRESIneo载体中获得核酸疫苗质粒,经筛选鉴定后,将上述核酸疫苗质粒及空载体质粒pIRESIneo分别用脂质体瞬时转染CHO细胞,应用免疫印迹法检测核心抗原在体外CHO细胞中的表达,并将其免疫实验小鼠,以酶联免疫吸附法验证其免疫原性。结果:成功构建以pIRESIneo为载体的含tPA信号肽的HuZP3核心抗原核酸疫苗质粒,体外瞬时表达证实含tPA信号肽的HuZP3核心抗原在CHO细胞胞内和胞外均能表达,含tPA信号肽的HuZP3核心抗原核酸疫苗质粒的核心抗原表达水平较高,核酸疫苗质粒具有很好的免疫原性。结论:以pIRESIneo为载体的含tPA信号肽的HuZP3核心抗原核酸疫苗能够将细胞内的HuZP3核心抗原分泌到细胞外,构建的核酸疫苗质粒pIRES1-ZP3/tPA具有很好的免疫原性,为进一步研究其免疫原性奠定了基础。     

影响基因疫苗免疫效果的因素

基因免疫，即把外源目的基因克隆到真核表达载体，然后将重组的质粒DNA直接注射到动物体内，使外源基因在活体内表达，产生的抗原激活机体的免疫系统，引发免疫反应。Wolff等(1990年)发现小鼠的骨骼肌细胞能捕获含外源基因的质粒并表达外源基因，首次提出了基因免疫的概念。Tang等(1992年)将含生长激素基因的质粒导入小鼠表皮细胞，88％的被免疫小鼠产生了抗生长激素抗体，二次免疫后抗体水平显著提高。迄今已报道的DNA疫苗主要用于疾病防疫(如流感、艾滋病、结核病、肝炎、疟疾、科什曼病、牛疱疹病毒、狂犬病、脑炎病毒以及多种癌基因疫苗)、生育控制(如兔透明带蛋白、精子表面蛋白SP16基因疫苗、抑制素基因疫苗)、生长调控(如生长抑素基因疫苗)等方面。由于影响DNA疫苗免疫效果的因素很多，导致DNA疫苗的免疫效果不一，本文就影响DRA疫苗免疫效果的因素作一综述。     

口服鼠疫F1-Ⅴ重组融合蛋白活菌疫苗的构建及免疫效果的初步研究

鼠疫耶尔森菌能产生很多由染色体或质粒编码的毒力因子,包括pgm、pst、Yops、F1抗原、V抗原等。F1和V抗原已被证实为主要保护性抗原,且存在属间保守性,F1-V融合抗原分子在免疫原性和免疫保护性上具有叠加效应,将两者联合接种可保护小鼠抵抗10~9 LD_(50)强度攻击。在鼠疫杆菌基因组、蛋白组和功能基因组研究的基础上,F1和V是鼠疫新型疫苗研究首选的保护性抗原分子的靶标。现有鼠疫死菌苗和鼠疫活菌苗在剂型和接种方式没有黏膜保护作用,可能会因此影响疫苗的保护效果。沙门菌可有效提呈抗原到肠道的免疫系统,在肠道组织、肝脏中增殖,可持续诱导机体细胞、体液免疫和黏膜免疫。本实验通过含有asd基因的重组质粒     

以减毒沙门菌作为DNA疫苗载体的研究

目的 以真核表达质粒pCMVβ为报告基因，研究用芳香族氨基酸合成缺陷的沙门菌SL7207为载体以提高DNA疫苗免疫应答的可行性。方法 携带质粒pCMVβ的SL7207体外感染小鼠腹腔巨噬细胞后，用X-gal染色方法和RT-PCR方法检测巨噬细胞内β-gal的表达。小鼠口服免疫SL7207(pCMVβ)后，用RT-PCR方法检测β-gaⅠ基因在淋巴组织中的转录产物；用ELISA方法检测体液免疫；用^3H-TdR掺入法检测脾淋巴细胞增殖；用JAM试验检测杀伤性T淋巴细胞反应。结果 SL7207能有效地将质粒DNA传递到体外培养的巨噬细胞中并进行表达；小鼠口服携带有pCMVβ的SL7207后，能在脾脏、派伊尔结、肠系膜淋巴结中检测到目的基因的转录，并可诱导小鼠产生特异性体液免疫和细胞免疫。与肌内注射pCMVβ相比较，口服SL7207(pCMVβ)能更有效地诱导出细胞免疫应答。结论 减毒沙门菌SL7207作为DNA疫苗的载体，可经口服途径进行免疫，并可将质粒直接传递给抗原递呈细胞，诱导出以细胞免疫为主的免疫应答。     

轮状病毒脂质体DNA疫苗体内诱导免疫应答研究

目的:通过对轮状病毒脂质体DNA疫苗体内免疫应答研究,寻找轮状病毒DNA疫苗理想的免疫佐剂.方法:脂质体包被的轮状病毒基因疫苗pcDNA1/VP7及裸DNA经肌肉注射及鼻粘膜两种途径免疫BALB/c小鼠,利用ELISA方法对其诱导产生的体液免疫应答进行测定.结果:经裸DNA及脂质体包被的质粒DNA免疫小鼠后,滴鼻组和肌注组血清特异性IgG水平较对照组明显升高.值得注意的是,脂质体包被的质粒DNA经肌注接种后血清特异性IgA水平也较对照组明显升高,而其余各实验组均未能诱导血清特异性IgA水平的升高.结论:脂质体在DNA接种中不仅作为质粒DNA疫苗的载体,而且起到免疫佐剂的作用.经该脂质体包被的质粒DNA免疫小鼠后,肌注组血清IgA水平较对照组明显升高,提示该脂质体包被的DNA经肌肉注射途径接种可能对机体产生免疫保护.     

布氏杆菌pCDNA3.1-L7/L12核酸疫苗的构建及其免疫学评价

目的 获得布氏杆菌保护性抗原L2／L12重组蛋白及pCDNA3．1-L7／L12重组质粒，并比较其诱导特异性免疫应答的能力。方法 PCR扩增布氏杆菌核蛋白L7／L12基因分别构建至原核表达载体PET32a( )和真核表达载体pCDNA3.1( )中；pET32a-L7／L12重组质粒转化BL21(DE3)，所表达蛋白经SDS-PAGE、免疫印迹分析、纯化后免疫小鼠；pCDNA3.1-12／L12重组质粒配以GM-CSF同时肌肉注射免疫小鼠，3次免疫后测定免疫功能进行免疫效果的评价。结果ELISA、Western blot检测到免疫鼠体内有特异性抗体产生，蛋白苗所诱导的抗体效价远远高于DNA疫苗；通过淋巴细胞增殖实验、细胞因子和CD分子测定表明DNA疫苗以诱发TH1型免疫为主。结论 所构建的布氏杆菌DNA疫苗和蛋白苗均具有诱导特异性细胞和体液免疫应答的能力，DNA疫苗诱导产生的细胞免疫反应强于蛋白苗，可作为潜在的布氏菌新型疫苗，有进一步研究的意义。     

034 核酸疫苗抗原提呈机理研究进展

核酸疫苗即是将外源基因克隆到真核质粒表达载体上,然后将重组的质粒DNA直接注射到动物体内,使外源基因在活体内表达、产生抗原激活机体免疫系统,引起免疫反应.核酸疫苗为疫苗的研制提供了新的方法,但其引起的免疫机理尚不十分清楚.本文仅就核酸疫苗不同的免疫方式,包括皮内、肌肉和粘膜接种所涉及的抗原提呈机理作一综述.     

表达HIV-1 B亚型env基因的质粒DNA及腺病毒载体疫苗的免疫原性研究

目的 构建表达中国B亚型HIV-1流行株env基因的DNA及重组腺病毒载体疫苗,将其用于预防或治疗HIV感染.方法 构建质粒DNA疫苗pVR-gp160及重组腺病毒载体疫苗rAdV-gp160.将这两种疫苗以不同的方式免疫BALB/c小鼠,分别采用ELISPOT方法 和ELISA方法 检测免疫小鼠中HIV-1 Gp120特异性细胞免疫反应及抗体反应.结果 DNA疫苗单独免疫及DNA疫苗初免/腺病毒疫苗加强免疫的联合免疫方案皆可诱导较高水平的Gp120特异性细胞免疫反应;而在体液免疫方面,各实验组产生的Gp120特异性抗体水平都较低.结论 所构建的DNA疫苗及rAdV疫苗能有效表达Gp160蛋白,并可有效激活机体的细胞免疫反应.     

SARS冠状病毒S蛋白C端片段基因的克隆及其DNA疫苗的免疫学研究

目的：构建抗原基因为SARS冠状病毒（Severe acute respiratory syndrome coronavirus，SARS-CoY）S蛋白C端片段基因的DNA疫苗，采用肌注和滴鼻的方法接种小鼠后观察肌肉注射途径和黏膜途径免疫使机体产生免疫应答的情况。方法：将S蛋白C端片段克隆至真核表达载体pcDNA3．1（-），随之将重组质粒进行小鼠肌肉和黏膜免疫，定期检测外周血中抗SARS-CoV的病毒特异性抗体水平，流式细胞仪观察其淋巴细胞表型变化，免疫组化检测抗原表达分布，脾细胞增殖实验评价CTL效果。结果：疫苗注射后15天就能在血清中检测出病毒特异性抗体。随着时问的延续，抗体水平逐步升高，至30天后达到稳定，以CTL为主的CD8^＋T淋巴细胞的百分比含量增加极显著，引起强大的体液免疫和细胞免疫；疫苗滴鼻后45天可在鼻黏膜检测到抗原表达；而空载体质粒对照组未检测出明显的特异性免疫应答。结论：以S蛋白C端片段基因为抗原基因的DNA疫苗通过肌注和滴鼻能诱导小鼠针对SARS病毒强大的免疫应答。     

汉滩病毒核酸疫苗滴鼻及肌注免疫小鼠效果的比较研究

观察汉滩病毒DNA疫苗滴鼻及肌注免疫诱导机体产生的免疫应答,探索汉滩病毒DNA疫苗新的免疫途径。以pcDNA3.1B-S1.3进行肌肉注射及滴鼻免疫小鼠,采用ELISA、淋巴细胞转化试验及特异性CTL杀伤活性测定等方法检测其诱导的系统和黏膜免疫反应的差异。实验结果表明,滴鼻组粪IgA滴度明显高于肌注组(P<0.05);而肌注组血IgG滴度均值虽高于滴鼻组,但两者统计上无显著意义(P>0.05);滴鼻组及肌注组小鼠脾细胞分别经ConA刺激后,其刺激指数作统计分析,结果无显著性差别(P>0.05);肌注组与滴鼻组效应细胞对靶细胞的杀伤力用方差分析进行比较,无显著性差异(P>0.05)。这些均表明,滴鼻免疫对特异的黏膜免疫激发作用明显优于肌肉注射,疫苗的滴鼻免疫途径较肌注途径有着明显的优势。     

壳聚糖介导增强幽门螺杆菌Lpp20 DNA疫苗黏膜免疫效果的研究

目的 探讨壳聚糖包裹DNA疫苗黏膜免疫效果.方法 采用复凝聚法制备载幽门螺杆菌脂蛋白 Lpp20基因的壳聚糖(CS)纳米粒(NPs),并对CS/DNA纳米粒的特质进行研究;用载基因壳聚糖纳米粒黏膜免疫(滴鼻和口服)小鼠,检测免疫小鼠的细胞和体液免疫水平.结果 裸质粒pcDNA3.1(+)/Lpp20与CS/DNA NPs通过黏膜免疫均能诱导小鼠产生有效的免疫应答.CS/DNANPs滴鼻和口服免疫组诱导的抗体明显升高,与裸质粒组相比有明显差异(P＜0.05),同时CS/DNANPs滴鼻和口服免疫组小鼠脾淋巴细胞经特异性抗原刺激后,刺激指数及培养上清中IFN-γ和IL-4含量明显高于裸质粒组、壳聚糖组和PBS组,且滴鼻免疫组高于口服组.结论 壳聚糖纳米粒能增强pcDNA3.1(+)/Lpp20核酸疫苗的黏膜免疫(滴鼻和口服免疫)效果;载Lpp20基因壳聚糖纳米粒滴鼻免疫比口服免疫能诱导更强的细胞和体液免疫应答.

Abstract：

Objective To investigate the immune response of mucosal immunization of new chitosan(CS) nanoparticles coating DNA vaccine. Methods The chitosan nanoparticles containing plasmid DNA encoding H. pylori lipoprotein Lpp20 gene were prepared using a complex coacervation method and then its speciality were analyzed. We then administered the naked plasmid DNA and chitosan-DNA nanoparticles to 6-week-old female BALB/c mice by intranasal or oral mucosal routes to observe the humoral and cellular immune responses. Results Naked plasmid pcDNA3.1 ( + )/Lpp20 and chitosan-pcDNA3. 1 ( + )/Lpp20 nanoparticles both induced effective immune response in mice through mucosal vaccination. Specific IgG and sIgA antibodies of chitosan-pcDNA3. 1 ( + )/Lpp20 nanoparticles groups were higher than that of naked pcDNA3.1 ( + )/Lpp20 group. The concentration of cytokines IFN-γ and IL-4 in cultural supernatant of T lymphocytes from chitosan-pcDNA3. 1 ( + )/Lpp20 nanoparticles immunized mice increased greatly than that of control groups. After stimulated by corresponding antigen, the stimulation index of intranasal or oral delivery of chitosan-pcDNA3. 1 ( + )/Lpp20 nanoparticles group was significantly higher than that of pcDNA3.1( + )/Lpp20 group, CS group and PBS control group. Moreover, systemic and mucosal immune responses in mice induced by intranasal immunization were stronger than that of oral immunization. Conclusion Chitosan nanoparticles enhanced the immune response of pcDNA3.1 ( + )/Lpp20 DNA vaccine by intranasal or oral administration in BALB/c mice. Compared to oral administration, intranasal delivery of chitosan-pcDNA3.1 ( + )/Lpp20 DNA nanoparticles could induce stronger cellular and humoral immune responses in BALB/c mice.     

口服疫苗与肠粘膜免疫效应机制

口服疫苗可有效激发肠粘膜免疫,给药途径简单、安全,且种类繁多,主要包括菌苗、病毒疫苗、蛋白质亚单位疫苗、合成肽疫苗、基因缺失疫苗、DNA疫苗及转基因植物疫苗等,口服疫苗运载体由病毒运载体、细菌运载体和微粒子运载体组成,口服疫苗佐剂在粘膜免疫中发挥重要作用。口服疫苗首先要克服的障碍就是口服无反应性,口服疫苗产生的免疫力可以通过共同膜机制遍布全身膜系统,可明显刺激全身性的细胞免疫和体液免疫应答。     

Host and bacterial factors affecting induction of immune responses to flagellin expressed by attenuated Salmonella vaccine strains

Previous observations demonstrated that the delivery of recombinant Salmonella enterica serovar Dublin strains to mice via mucosal routes did not efficiently activate systemic and secreted antibody responses to either type d flagellin or genetically fused heterologous B-cell epitopes, thus reducing the usefulness of the protein as a carrier of epitopes for vaccine purposes. In this work, we investigated murine systemic and mucosal flagellin immunogenicity after oral immunization with attenuated Salmonella strains. The reduced anti-type d flagellin antibody responses in mice immunized via mucosal routes with three doses of flagellated S. enterica serovar Dublin strains were not caused by oral tolerance and could not be restored by coadministration of a mucosal adjuvant. The induction of antibody responses to Salmonella flagellins was shown to differ according to the genetic background, but not the haplotype, of the mouse lineage. Moreover, BALB/c mice orally immunized with S. enterica serovar Typhimurium strains developed anti-type i flagellin sera and secreted antibody responses, which indicated that the serovar of the Salmonella vaccine strain also affected flagellin immunogenicity. Analyses of cytokine responses of BALB/c mice immunized with three oral doses of flagellated S. enterica serovar Dublin vaccine strains showed that, in spite of the lack of antibody responses, elevated type d flagellin-specific CD4-cell-activation-dependent gamma interferon (IFN-gamma) and interleukin-10 responses were elicited after the administration of the vaccine strains via either parenteral or mucosal routes. Similar cytokine production patterns were detected to a T-cell heterologous epitope, derived from the CFA/I fimbriae of enterotoxigenic Escherichia coli (ETEC), in mice orally immunized with a Salmonella vaccine strain expressing hybrid flagella. These results indicate that the immunogenicities of Salmonella flagellins can differ significantly, depending on the murine host and on the bacterial vector used, and demonstrate that the induction of CD4-cell-activation-dependent IFN-gamma production represents a major immune response triggered by flagellin and in-frame fused heterologous T-cell epitopes after the oral administration of recombinant S. enterica serovar Dublin vaccine strains.     

Use of lambda phage S and R gene products in an inducible lysis system for Vibrio cholerae- and Salmonella enterica serovar typhimurium-based DNA vaccine delivery systems

Novel methods for adapting DNA vaccine technology to the prevention of mucosal diseases are greatly needed. Here we show that regulated expression of phage lambda lysis genes S and R causes dramatic lysis of both Vibrio cholerae and Salmonella enterica serovar Typhimurium cells with concomitant release of plasmid DNA into the surrounding media. We also used single and double DNase mutant strains to show that secreted V. cholerae DNases can adversely affect the integrity of DNA molecules released upon lysis. These results suggest that incorporation of lambda SR-mediated lysis constructs and DNA stabilizing mutations into candidate live attenuated bacterial vaccines offers a promising approach for the development of effective mucosal DNA delivery vectors for humans.     

Naked PCV-2 cloned genomic DNA is infectious by mucosal (intratracheal or oro-nasal) inoculation

Porcine circovirus type 2 (PCV-2) is involved in several diseases named porcine circovirus-associated diseases and is transmitted by oro-faecal route. In this study we inoculated porcine-circovirus free piglets by mucosal routes (intratracheal or oro-nasal routes) with a plasmid carrying two copies of PCV-2 genomic DNA and compared the results to the intramuscular route. We observed that this PCV-2 naked DNA serves as template for viral replication and infectious PCV-2 particles are detected in the whole body after parenteral (intramuscular) or mucosal (intratracheal or oro-nasal) delivery. These results suggest that PCV-2 genome could play a role in in vivo transmission.     

优化密码对牛乳头瘤病毒L1基因粘膜免疫的增强作用

为探讨优化密码对牛乳头瘤病毒 1型主要晚期基因 (BPV1L1)免疫原性的影响 ,分别将含野生型和优化密码的人源化BPV1L1基因的真核表达质粒转入减毒沙门菌S BRD5 0 9后 ,通过滴鼻、阴道免疫、静脉注射、腹腔注射等途径免疫小鼠 ,经VLPELISA方法测定抗L1构象性抗体产生 ,MTT法观察诱导的特异性细胞免疫反应。抗体检测结果显示 ,经粘膜免疫途径 ,与含有野生型L1基因的表达质粒pcDNA3WBPVL1相比 ,含优化密码L1基因的pcDNA3HBPVL1诱导产生的SIgA、IgG明显升高 ,而细胞免疫反应无明显差异。表明优化密码能促进乳头瘤病毒晚期基因L1诱导的体液免疫反应 ,减毒沙门菌是PVL1DNA疫苗粘膜免疫的有效载体。     

New generation of mucosal adjuvants for the induction of protective immunity

Invasion of infectious agents through mucosal surfaces can be prevented by use of the common mucosal immune system (CMIS), which interconnects inductive tissues, including Peyer's patches (PPs) and nasopharyngeal-associated lymphoreticular tissue (NALT), and effector tissues of the intestinal and respiratory tracts. In order for the CMIS to induce maximal protective mucosal immunity, co-administration of mucosal adjuvant has been shown to be essential. When vaccine antigen is administered together with mucosal adjuvant, antigen-specific T-helper (Th) 1 and Th2 cells, cytotoxic T lymphocytes (CTLs) and IgA B cell responses are effectively induced by oral or nasal routes via the CMIS. In the early stages of induction of mucosal immune response, the uptake of orally or nasally administered antigens is achieved through a unique set of antigen-sampling cells, M cells located in follicle-associated epithelium (FAE) of inductive sites. After successful uptake, the antigens are immediately processed and presented by the underlying dendritic cells (DCs). Elucidation of the molecular/cellular characteristics of M cells and mucosal DCs will greatly facilitate the design of a new generation of effective mucosal adjuvants and of a vaccine delivery vehicle that maximises the use of the CMIS. Our recent efforts at mucosal vaccine development have focused on nasal administration of vaccine antigen together with nontoxic mutant-based or cytokine-/chemokine-based adjuvant for the induction of the protective immunity. To this end, a chimeric form of a nontoxic adjuvant combining the merits of mutant cholera toxin A subunit (mCT-A) and heat labile toxin B subunit (LT-B) was created as the second generation of detoxified toxin-based mucosal adjuvant. When a vaccine antigen was coexpressed together with an immune stimulatory/delivery molecule in crop seed, this edible vaccine is not only effective but also extremely practical in that it can be produced in huge quantities and preserved and shipped over long distances at room temperature without altering the quality of the vaccine. Because such qualities would greatly facilitate global vaccination, this new generation edible vaccines with a built-in adjuvant and/or M cell-targeted edible vaccine promises to be a powerful weapon for combating infectious diseases and bioterrorism.     

Recruitment of different subsets of antigen-presenting cells selectively modulates DNA vaccine-elicited CD4+ and CD8+ T lymphocyte responses

The immunogenicity of plasmid DNA vaccines may be limited by the availability of professional antigen-presenting cells (APC) at the site of inoculation. Here we demonstrate that the types of APC recruited to the injection site can selectively modulate CD4(+) or CD8(+) T lymphocyte responses elicited by an HIV-1 Env DNA vaccine in mice. Coadministration of plasmid GM-CSF with the DNA vaccine resulted in the recruitment of macrophages to the site of inoculation and specifically augmented vaccine-elicited CD4(+) T lymphocyte responses. In contrast, coadministration of plasmid MIP-1 alpha with the DNA vaccine resulted in the recruitment of dendritic cells to the injection site and enhanced vaccine-elicited CD8(+) T lymphocyte responses. Interestingly, coadministration of both plasmid GM-CSF and plasmid MIP-1 alpha with the DNA vaccine recruited both macrophages and dendritic cells and led to a synergistic and sustained augmentation of CD4(+)and CD8(+) T lymphocyte responses. These data demonstrate the critical importance of locally recruited professional APC in determining the magnitude and nature of immune responses elicited by plasmid DNA vaccines. Moreover, these studies show that different subsets of professional APC can selectively modulate DNA vaccine-elicited T lymphocyte responses.