刚地弓形虫SRS29C核酸疫苗的构建及SRS29C与SAG1联合免疫保护性的比较研究

为了探究刚地弓形虫表面蛋白(surface antigen, SAG)SRS29C基因和SRS29C、SAG1联合基因的核酸疫苗对小鼠急性感染弓形虫的免疫保护效果，试验利用PCR方法扩增了SRS29C基因片段并将其克隆至真核表达载体pEGFP-N1中，构建重组质粒pEGFP-SRS29C,并对该质粒进行酶切鉴定，同时用该质粒对HEK293T细胞进行转染，再用Western-blot方法检测目标蛋白在细胞中的表达情况；用重组质粒pEGFP-SRS29C和pEGFP-SAG1单独免疫或联合免疫小鼠，用ELISA法测定血清IgG水平，CCK-8法检测脾淋巴细胞增殖能力，流式细胞仪测定CD₄⁺和CD₈⁺T淋巴细胞百分比，ELISA试剂盒检测脾脏细胞因子的表达情况；进行小鼠体内攻虫试验，记录小鼠存活时间。结果表明：成功构建了重组质粒pEGFP-SRS29C,表达的蛋白质大小为66 ku; pEGFP-SRS29C组和联合免疫组与PBS组和空载体组相比血清IgG含量、脾淋巴细胞增殖率、CD4⁺     

嵌合型猪圆环病毒（PCV1—2）及PCV2 ORF2真核表达质粒对商品猪的免疫保护

应用本实验室构建的嵌合型猪圆环病毒（PCV1—2）及真核表达质粒pcDNA3．1／V5-His-ORF2作为免疫原免疫母源抗体ELISA效价在0．07～0．60不等的商品猪,9头猪随机分为4组,1组（3头）肌肉注射免疫10^3.5 TCID50的PCV1-2／头,2组（2头）肌肉注射真核表达质粒200μg／头,3组（2头）肌肉注射空载体（pcDNA3．1）200μg／头,4组（2头）不免疫作为攻毒对照组。于免疫后42d,PCV1—2组及真核表达质粒组产生了PCV2抗体。免疫后42d所有组攻毒PCV2和PRRSV,剂量分别为2×10^4.5 TCID50／头和10^6 TCID50／头。攻毒后21d,攻毒对照组猪淋巴结比免疫组显著肿大,免疫组猪血清、淋巴结中PCV2病毒栽量低于对照组,攻毒对照组猪淋巴结中PCV2抗原含量高于免疫组。这些结果表明,嵌合型PCV1-2及真核表达质粒肌肉注射免疫商品猪后,对PCV2感染能产生保护性免疫应答,有可能成为候选疫苗。     

嵌合型猪圆环病毒(PCV1-2)及PCV2 ORF2真核表达质粒对商品猪的免疫保护

应用本实验室构建的嵌合型猪圆环病毒(PCV1-2)及真核表达质粒pcDNA3.1/V5-His-ORF2作为免疫原免疫母源抗体ELISA效价在0.07～0.60不等的商品猪,9头猪随机分为4组,1组(3头)肌肉注射免疫103.5TCID50的PCV1-2/头,2组(2头)肌肉注射真核表达质粒200μg/头,3组(2头)肌肉注射空载体(pcDNA3.1)200 μg/头,4组(2头)不免疫作为攻毒对照组.于免疫后42 d,PCV1-2组及真核表达质粒组产生了PCV2抗体.免疫后42 d所有组攻毒PCV2和PRRSV,剂量分别为2×104.5TCID50/头和106TCID50/头.攻毒后21 d,攻毒对照组猪淋巴结比免疫组显著肿大,免疫组猪血清、淋巴结中PCV2病毒载量低于对照组,攻毒对照组猪淋巴结中PCV2抗原含量高于免疫组.这些结果表明,嵌合型PCV1-2及真核表达质粒肌肉注射免疫商品猪后,对PCV2感染能产生保护性免疫应答,有可能成为候选疫苗.     

弓形虫蛋白质二硫键异构酶的免疫保护作用

为了探讨皮下免疫弓形虫蛋白质二硫键异构酶(TgPDI)对弓形虫急性感染的保护作用,本试验通过原核表达获取了重组TgPDI,将纯化并去除内毒素的重组蛋白皮下免疫昆明小鼠,利用ELISA方法监控抗体水平变化,通过实时荧光定量PCR检测感染小鼠的组织载虫量并记录小鼠存活时间,评价TgPDI的免疫保护作用。结果显示,免疫重组TgPDI可以有效刺激小鼠产生抗体(1∶16 000);免疫该蛋白可以极显著抑制弓形虫感染小鼠血液、肝脏、脾脏和脑组织中的弓形虫增殖(P0.01),并能延长小鼠感染后的存活时间。结果表明,皮下免疫重组TgPDI可以刺激小鼠产生保护性免疫应答,TgPDI是预防弓形虫感染的免疫候选分子。     

新城疫热稳定性天然弱毒B95株核酸疫苗的构建

将含有新城疫热稳定性天然弱毒B95株F基因的重组克隆质粒pGEM—F用Not Ⅰ单酶切，电泳回收纯化目的片段，与同样用NotⅠ单酶切并经去磷酸化处理的真核表达载体pcDNA3．1连接，构建了新城疫核酸疫苗，并用所构建的新城疫核酸疫苗与载基因阳离子脂质体结合进行了免疫试验，通过ELISA、淋巴细胞转化试验检测了核酸疫苗在鸡体内的表达。结果显示，表达产物作为抗原物质刺激机体产生了特异性应答反应，引起了机体特异性的体液免疫和细胞免疫，对新城疫强毒攻击的保护率为75%。     

猪圆环病毒2型核酸疫苗的小鼠免疫保护试验

为了研究猪圆环病毒2型(PCV2)核酸疫苗在小鼠攻毒试验中的免疫保护效果,以PCV-2 GXWZ-1株为模板,扩增出ORF2基因及其截短基因8个片段(A(ORF2)、B(51-100aa)、C(101-150aa)、D(181-235aa)、E(151-200aa)、F(51-150aa)、G(101-235aa)、H(51-235aa)),将其插入到pcDNA3.0载体中,构建出真核表达质粒,并将其转染至PK-15细胞,用间接免疫荧光试验检测其瞬时表达情况。将试验小鼠随机分成9组,其中免疫组7组,阴阳性对照各1组,将纯化的真核表达质粒对小鼠进行组合免疫;二免后,用经处理过的PCV-2 GXWZ-2株阳性病料悬液腹腔注射免疫组和非免疫对照组小鼠,阴性对照组用生理盐水腹腔注射;其后进行体重记录、病理切片制作及PCR检测。结果表明:共有6个真核表达质粒成功在PK-15细胞中表达。在攻毒后的3周内,阳性对照组小鼠PCR诊断均为阳性;免疫组中,部分组小鼠在攻毒后第1周或在第2周为阳性,到第3周时各免疫组小鼠全部为阴性;阴性对照组始终为阴性。免疫组在病理保护学方面明显优于非免疫对照组,非免疫对照组的体重增长速率略低于免疫组和阴性对照组。由此可见猪圆环病毒2型核酸疫苗在小鼠攻毒试验中有明显的保护作用。     

弓形虫GJS株pcDNA3-MIC3核酸疫苗的研究

根据GenBank中MIC3基因序列设计1对引物,采用PCR技术从弓形虫GJS株基因组DNA中扩增微线体蛋白3(MIC3)基因片段,克隆到pMD18-T载体,经PCR、酶切及测序鉴定后,阳性重组质粒酶切并亚克隆到真核表达载体pcDNA3.1(+)后进行PCR、酶切及测序鉴定.重组质粒pcDNA3-MIC3肌肉注射免疫BALB/c小鼠,通过ELISA检测血清特异抗体;经腹腔攻击感染弓形虫GJS株速殖子,观察小鼠的生存时间.结果成功构建了pcD-NA3-MIC3质粒;免疫组小鼠血清检测到特异性抗体;攻击感染后免疫组小鼠平均存活时间较对照组明显延长.表明该核酸疫苗具有较好的免疫原性,能诱导小鼠产生良好的免疫保护作用.     

弓形虫MIC3亚单位疫苗的免疫效果观察

将重组的弓形虫微线体蛋白MIC3(rMIC3)25μg以皮下注射的方式,间隔2周3次免疫Balb/c小鼠,同时设相同剂量的谷胱甘肽转移酶(GST)和磷酸盐缓冲液(PBS)对照组.以酶联免疫吸附试验(ELISA)检测试验小鼠血清特异性抗体,并在3免后腹腔接种弓形虫RH株速殖子1×103个/鼠,观察其免疫保护效果.结果表明,与GST和PBS对照组小鼠相比,rMIC3组试验小鼠在3免后的ELISA抗体水平极显著提高(P＜0.01),免疫小鼠的生存时间明显延长(P＜0.05).上述结果为研制弓形虫基因工程亚单位疫苗奠定了基础.     

4株布鲁氏菌弱毒株对小鼠毒力及免疫保护力的评价

为检测国内外已有的布鲁氏菌疫苗株S19、M5、S2和RB51的胞内存活力、毒力、免疫保护力以及抗体消长水平,将上述4种疫苗株,分别以100:1的MOI侵染小鼠巨噬细胞,结果发现RB51的胞内存活力最强;以1×10~6 CFU/只免疫昆明小白鼠,测定各疫苗株在小鼠脾脏中的定居力,结果发现M5的定居力最强;待疫苗株在小鼠体内被清除后,以1×10~5 CFU/只腹腔接种2308毒株,进行攻毒试验,检测各疫苗株的保护力,结果发现M5的保护效果最好;免疫后连续10周采集血清,用ELISA检测血清中的Ig G滴度、IFN-γ的表达水平及抗体消长水平,结果发现S2、M5组的Ig G水平高于其他组,而各组间的IFN-γ水平差异不显著(P0.05);分别用虎红平板凝集试验(RBPT)和标准试管凝集试验(SAT)检测血清凝集状况,结果发现S2、S19组的抗体持续时间较长;剖检各疫苗株对小鼠脾脏、肝脏、肾脏等组织引起的病理学变化,结果发现M5引起的病变程度最强。     

纹皮蝇HypoderminC基因真核表达质粒构建及小鼠免疫试验

根据GenBank发表的Hypodermin C(HC)基因序列设计引物,以原核表达载体pET-HC为模板,PCR扩增HC基因,将克隆基因插入到真核表达载体pVAX1中,构建重组真核表达质粒pVAX1-HC。将重组质粒pVAX1-HC转染小鼠胎儿成纤维细胞,以间接免疫荧光法检测HC基因在细胞中表达。用真核表达质粒pVAX1-HC经双侧胫前肌注射昆明小鼠,对小鼠进行体液免疫和细胞免疫研究。结果表明,小鼠血清抗体水平和淋巴细胞增殖水平明显高于非免疫对照组。本研究成功构建了真核表达质粒pVAX1-HC,为纹皮蝇核酸疫苗研发奠定了基础。     

Immune response and protective efficacy against homologous challenge in BALB/c mice vaccinated with DNA vaccine encoding Toxoplasma gondii actin depolymerizing factor gene

A DNA vaccine (pVAX1-TgADF) encoding Toxoplasma gondii actin depolymerizing factor (ADF) gene was constructed and the immune response and protective efficacy of this vaccine against homologous challenge in BALB/c mice were evaluated. High titers of specific antibody and increases in the percentage of CD4(+) and CD8(+) T lymphocyte cells were observed from BALB/c mice vaccinated with pVAX1-TgADF (P<0.05), when PBS group was used as control. The survival time of BALB/c mice in pVAX1-TgADF group was longer than those in control groups. The numbers of brain cysts in the experimental BALB/c mice immunized with pVAX1-TgADF reduced significantly compared with those in PBS group (P<0.05), and the rate of reduction could reach to around 42.8%. These results suggested that the DNA vaccine pVAX1-TgADF could generate specific humoral and cellular immune responses, prolong survival times, and reduce brain cysts load against T. gondii infection in BALB/c mice.     

Induction of immune responses in sheep by vaccination with liposome-entrapped DNA complexes encoding Toxoplasma gondii MIC3 gene

Toxoplasma gondii is a parasite that has been extensively studied due to its medical and veterinary importance in terminating pregnancies. Consequently, a satisfactory vaccine is required to control its adverse effects on pregnant animals. The microneme protein, MIC3, is a major adhesion protein that binds to the surface of host cells and parasites, and is therefore a potential vaccine against T. gondii. The viability of MIC3 as a vaccine is investigated in this study. Sheep were injected twice, intramuscularly, with plasmids containing DNA encoding for the mature form of MIC3 protein formulated into liposomes. Control sheep were injected with an empty vector or received no injections. The injection of sheep with DNA plasmids encoding for MIC3 elicited an immune response after the first and second injections as indicated by antibody responses and the production of IFN-gamma. The immune response, as measured by the IgG2 and IgG1 serum levels, was boosted after the injection of the MIC3 DNA vaccine together with high anti-MIC3 antibodies. The results demonstrate that the intramuscular injection of sheep with a plasmid containing DNA coding for MIC3 protein induces a significant and effective immune response against T. gondii.     

Vaccination with a novel multi-epitope ROP8 DNA vaccine against acute Toxoplasma gondii infection induces strong B and T cell responses in mice

Rhoptry proteins (ROPs) are involved in the cell invasion and parasitophorous vacuole (PV) formation and also vital for survival of Toxoplasma gondii (T. gondii) within host cells. ROP8 have a main role during the early phase of infection and can express in tachyzoite and bradyzoite forms. In the present study, we designed a novel multi-epitope DNA vaccine encoding the potential B and T-cell epitopes from ROP8 protein to evaluate the immunity and protective efficacy against acute T. gondii infection in BALB/c mice. For this purpose, several bioinformatics online servers were used. At first, the potential epitopes were selected for T and B cells using immune epitope database (IEDB) and BCPREDS online services. Then, the selected epitopes were fused together by SAPGTP linker. Finally, the physico-chemical features, secondary and tertiary structures, antigenicity, and allergenicity of the peptide were evaluated through different bioinformatics tools. Lastly, the multi-epitope peptide was successfully cloned into pcDNA3.1 expression vector. The DNA vaccine was subcutaneously injected into BALB/c mice and the immune responses of the vaccinated mice and controls were determined. The obtained results revealed that the multi-epitope ROP8 peptide has 183 amino acid residues with average molecular weight (MW) of 18.974 kDa. More than 98 % residues of the peptide were incorporated in favored and allowed regions of the Ramachandran plot. The antigenicity of multi-epitope peptide were estimated 0.8751 and 0.7649 by ANTIGENpro and VaxiJen servers, respectively. BALB/c mice immunized with DNA vaccine showed significantly increased the level of specific anti-T. gondii antibodies (P < 0.05), and a mixed IgG1/IgG2a response with predominance of IgG2a production. The immunized mice also displayed a TH1-type cellular immune response with production of IFN-γ and prolonged survival time, compared with the control groups (P < 0.05). The findings revealed that the multi-epitope ROP8 DNA vaccine induced strong humoral and cellular responses and prolonged the survival time in BALB/c mice, suggesting selection of potential epitopes may be a promising strategy for the design of multi-epitope-based vaccines.     

犬恶丝虫硫氧还蛋白过氧化物酶真核表达质粒的构建及初步免疫试验

为评价犬恶丝虫硫氧还蛋白过氧化物酶(TPx)真核表达质粒的免疫原性,本实验利用RT-PCR方法扩增TPx基因,将其克隆于真核表达载体pVAX1中构建重组质粒pVAX1-TPx,并对其进行体外表达鉴定及通过特异性抗体水平及相关的免疫因子的检测,评价其在体内诱导的免疫反应.实验结果表明,将pVAX1-TPx转染于Cos7细胞中能够正确表达TPx,其分子量约为28 ku,并被阳性血清所识别.将pVAX1-TPx免疫BALB/c小鼠并采用ELISA检测结果显示,重组质粒免疫组的外周血中抗体、Th2细胞分泌的IL4及IL13细胞因子水平均显著高于空质粒及空白对照组(p＜0.05);但Th1分泌的IFN-γ及IL2水平差异不显著.此外,淋巴细胞增殖试验结果也表明,pVAX1-TPx免疫组显著高于其他两个对照组(p＜0.05).实验数据表明pVAX1-TPx免疫可以有效诱导特异性的体液和细胞免疫.     

Toxoplasma gondii rhomboid protein 1 (TgROM1) is a potential vaccine candidate against toxoplasmosis

Infection with the intracellular protozoan parasite Toxoplasma gondii causes serious public health problems and is of great economic importance worldwide. The rhomboid proteins which are responsible for adhesion and invasion of host cells have been suggested as vaccine candidates against toxoplasmosis. A DNA vaccine (pVAX-ROM1) encoding T. gondii rhomboid protein 1 (TgROM1) gene was constructed and the immune response and protective efficacy of this vaccine against lethal challenge in BALB/c mice were evaluated. The results indicated that specific antibody and lymphocyte proliferative responses were elicited in mice receiving pVAX-ROM1. The production levels of IFN-γ, IL-2, IL-4, and IL-10, as well as the percentage of CD4(+) cells in mice vaccinated with pVAX-ROM1 were significantly increased respectively, compared to controls receiving either pVAX1 alone or PBS. After lethal challenge, the mice immunized with pVAX-ROM1 showed an increased survival time compared with the mice in the controls. Our data suggested that a DNA vaccine pVAX-ROM1 encoding T. gondii rhomboid protein 1 triggered strong humoral and cellular responses, and prolonged survival time against T. gondii infection in BALB/c mice.     

Evaluation of immune responses induced by SAG1 and MIC3 vaccine cocktails against Toxoplasma gondii

The aim of this study was to evaluate the immune responses of a SAG1 and MIC3 vaccine cocktail in BALB/c mice. Ninety-six BALB/c mice were randomly divided into eight groups, including three plasmid DNA vaccine groups (pcDNA-MIC3, pcDNA-SAG1, pcDNA-MIC3+pcDNA-SAG1), three recombinant pseudotype baculovirus vaccine groups (BV-G-MIC3, BV-G-SAG1, BV-G-SAG1+BV-G-MIC3) and two control groups (PBS and BV-G-EGFP). All groups were immunized intramuscularly twice at three-week intervals. The production of anti-Toxoplasma gondii lysate antigen (TLA) antibodies, lymphoproliferation, levels of IFN-γ, IL-4 and IL-10 and the survival time were monitored after vaccination. The results showed that immunization of BALB/c mice with MIC3 and SAG1 vaccines stimulated both the cellular and humoral immune responses with the production of anti-T. gondii TLA antibodies. The vaccine cocktails of pcDNA-MIC3+pcDNA-SAG1 or BV-G-SAG1+BV-G-MIC3 induced significantly higher immunogenicity than a single-gene vaccine (P<0.05). Splenocytes from the immunized mice significantly proliferated in response to the TLA and released interferon (IFN)-γ (P<0.05). However, the levels of IL-4 and IL-10 in the sera of the immunized mice were not significantly different from those of the controls (P>0.05). Immunization with the vaccine cocktail (BV-G-SAG1+BV-G-MIC3) in mice significantly prolonged survival (50%; P<0.05) against a lethal challenge of T. gondii (RH tachyzoites), while all mice in the other immunized groups and control groups died within 20 and 4 days post-infection, respectively. Furthermore, the recombinant pseudotype baculovirus vaccines induced better immunogenicity than the plasmid DNA vaccines (P<0.05). These results suggest that an excellent vector-mediated vaccine cocktail strategy might be used to develop a new generation of vaccines against T. gondii infection.     

Induction of protective immune response in mice by a DNA vaccine encoding Trypanosoma evansi beta tubulin gene

Surra, caused by Trypanosoma evansi, is an economically important veterinary disease of the tropics. Lack of effective drugs or vaccines have made surra a severe economic burden particularly in Asia and sub-Saharan Africa. In this study, a naked DNA construct encoding full length T. evansi beta (β) tubulin gene was used to immunize mice, to elicit a T. evansi β tubulin protein specific humoral immune response, delineated by ELISA. The serum cytokine profile post immunization, as determined by flow cytometry bead based assay, showed a predominant T helper cell Type 1 (Th1) response with significant increase in levels of IFNγ and TNFα. Lethal challenge with T. evansi blood-form trypomastigotes post immunization generated a β tubulin specific recall response and a stronger Th1 type serum cytokine profile which correlated with an extended survival and better control of parasitemia in the immunized mice.     

鸡堆型艾美耳球虫Hsp90克隆表达及其核酸疫苗的免疫保护作用

利用RT-PCR方法从鸡堆型艾美耳球虫(E.acervulina)子孢子中成功克隆热休克蛋白90(Hsp90)基因,并构建其原核和真核表达质粒pET30a-Hsp90和pVAX-Hsp90。重组表达的89 kD可溶蛋白免疫家兔制备多克隆抗体,间接ELISA和Western-Blot表明,其反应性和特异性良好。真核表达质粒pVAX-Hsp90体外瞬时转染间接免疫荧光检测可见成功表达。雏鸡真核表达质粒免疫后进行攻虫保护试验,结果表明,pVAX-Hsp90组较空载体组及PBS组增重极明显(P0.01),且肠道病变减轻,OPG减少,抗球虫指数为166.17。综上初步评价了Hsp90核酸疫苗的免疫保护作用,表明Hsp90是一种潜在的鸡球虫保护性抗原。