Divalent Cp15–23 vaccine enhances immune responses and protection against Cryptosporidium parvum infection

Cryptosporidiosis, caused by Cryptosporidium parvum, is life‐threatening in individuals with compromised immune systems and a common serious primary cause of outbreaks of diarrhoea in newborn calves and goats. To date, no specific or effective therapy for cryptosporidiosis has been developed. There have been increasing efforts geared towards development of vaccines to control the disease. We have generated a divalent peptide vaccine candidate utilizing the Cp23 and Cp15 surface proteins of sporozoite of C. parvum that have been reported to be protective individually in certain animal models. We demonstrate that our vaccine candidate induced greater CD4⁺ T cell, comparable CD8⁺ T cell, significant Th1 cytokine and antibody responses against C. parvum in vaccinated mice in a direct comparison with the crude extract and single valent Cp23 vaccine and conferred partial protection against challenge of C. parvum. The study indicates that the fusion Cp15–23 vaccine protein is the better vaccine candidate and warrants further preclinical development for prevention of cryptosporidiosis.     

上皮细胞microRNAs防御微小隐孢子虫感染的先天性免疫调节作用

MicroRNAs(miRNAs)作为基因表达关键的转录后调节因子,参与调节上皮细胞防御微小隐孢子虫(Cryptosporidium parvum)感染的固有免疫应答。目前,已发现Let-7i, miR-98, miR-27b, miR-513, miR-221, miR-424和miR-503与防御C.parvum感染的固有性免疫调控机制有关,包括调控上皮细胞防御C.parvum感染的反应、启动被感染上皮细胞释放外质体,调控胆管上皮细胞炎性反应,调控TLR/NF-κB信号通路、抑制信号转导转录激活酶蛋白的磷酸化,调控上皮细胞与T细胞的相互作用,以及调控iNOS和IL8 mRNA的稳定性等。本文综述了与C.parvum感染有关的miRNAs在调节宿主细胞固有性免疫反应方面的作用机制。     

微小隐孢子虫重组蛋白CP23与CP15/60-23免疫原性的研究

摘要: 目的 探讨微小隐孢子虫重组蛋白CP23与CP15/60-23 的免疫原性。 方法 用重组蛋白CP23与CP15/60-23分别免疫BALB/c小鼠,免疫3次,2周后检测抗CP23与CP15/60-23的特异性抗体IgG滴度、小鼠脾脏CD4+、CD8+T细胞及其培养上清中的细胞因子IFN-γ、IL-12,实验同时设PBS对照组;之后用微小隐孢子虫卵囊攻击免疫小鼠,收集小鼠粪便,计算小鼠排出的卵囊量。 结果 自免疫第2周特异性IgG抗体滴度水平逐渐升高,重组蛋白CP15/60-23组升高更为明显,免疫小鼠脾脏T细胞CD4+、CD8+百分比及CD4+/CD8+比值都增高,细胞因子 IFN-γ、IL-12的水平亦增加,与对照组比较差异均有统计学意义（P＜0.05）;卵囊攻击后,各组小鼠粪便中的卵囊数量都很低,各组之间无明显差异。 结论 重组蛋白CP23和CP15/60-23皆可产生较好的细胞及体液免疫反应,具有较强的免疫原性。     

微小隐孢子虫与安氏隐孢子虫Rhomboid基因部分序列的克隆和分析

目的获得我国微小隐孢子虫长春株与安氏隐孢子虫长春株Rhomboid基因（CPRho和CARho）部分序列并确定与国外分离株相应序列的同源性。方法应用RT-PCR技术扩增微小隐孢子虫长春株与安氏隐孢子虫长春株Rhomboid基因片段,然后将其克隆到pMD18-T载体中,测得序列应用DNAMAN软件进行序列分析。结果经RT-PCR扩增出微小隐孢子虫长春株与安氏隐孢子虫长春株Rhomboid基因部分序列,大小均为723bp。经DNAMAN软件分析,表明我国微小隐孢子虫长春株与安氏隐孢子虫长春株Rhomboid核苷酸序列同源性为99．6％,氨基酸同源性为99．2％。二者与GenBank公布的相应序列核苷酸同源性分别为99．9％和99．7％,而氨基酸同源性均为99．6％。结论获得了微小隐孢子虫长春株与安氏隐孢子虫长春株Rhomboid基因部分序列,为继续研究该基因的侵入功能等奠定了基础。     

微小隐孢子虫子孢子表面抗原CP23融合蛋白在大肠杆菌的表达

目的　构建微小隐孢子虫子孢子表面抗原CP2 3的原核表达载体 ,并且在大肠杆菌中表达。方法　用HindⅢ和EcoRⅠ酶分别从 pET - 2 8a(+)和 pMD18-T - 2 3质粒中酶切得到线性片段和CP2 3基因片段 ,然后用T4酶连接 ,构建重组的CP2 3的原核表达载体 ,在大肠杆菌BL2 1(DE3)中表达 ,并用SDS -PAGE、ELISA和Westernblotting进行鉴定。结果　构建了CP2 3的原核表达载体 ,得到了一分子量约为 14kDa的融合蛋白 ,占大肠杆菌总蛋白的 36 %。结论　CP2 3融合蛋白在大肠杆菌中得到了高效表达     

微小隐孢子虫感染对小鼠肠黏膜Toll样受体的影响

目的 探讨Toll样受体在微小隐孢子虫感染致小鼠肠黏膜损伤中的作用机制。 方法 30只雄性BALB/c小鼠随机分为正常对照组、感染1周组和感染2周组。用免疫抑制及卵囊灌胃的方法建立微小隐孢子虫肠道感染小鼠模型,感染1周组和2周组分别于感染后7 d和14 d剖杀,正常对照组于感染后14 d剖杀。光镜观察小鼠肠黏膜病理变化,并测量肠绒毛高度、隐窝深度及绒毛高度/隐窝深度比值;透射电镜观察小鼠肠黏膜超微结构;实时荧光定量PCR（qPCR）、Western blotting技术检测肠黏膜TLR2和TLR4表达情况。结果 光镜下,感染组小鼠肠绒毛水肿,明显萎缩变短,黏膜下层结构水肿,与肌层间形成间隙。与正常对照组比较,感染1周组和感染2周组小鼠空肠绒毛高度及绒毛高度/隐窝深度比值均明显降低（P均[<0.05]）,隐窝深度明显升高（P均 < 0.01）;且感染2周组小鼠空肠的绒毛高度及绒毛高度/隐窝深度比值均明显低于感染1周组（P均 < 0.05）,隐窝深度明显高于感染1周组（P < 0.01）。透射电镜显示,感染组小鼠的空肠可见微小隐孢子虫卵囊,结构完整,卵囊周围的肠绒毛严重脱落,呈火山口状,卵囊壁与上皮细胞膜融合。 qPCR结果显示,与正常对照组相比,感染1周组和感染2周组小鼠肠黏膜TLR2和TLR4 mRNA表达水平明显增高（P均[<0.05]）;且感染2周组小鼠较感染1周组小鼠TLR2和TLR4 mRNA表达水平明显增高（P均[<0.05]）。Western blotting检测结果表明,感染组小鼠肠黏膜TLR2和TLR4蛋白表达量较正常对照组显著增高（P均[<0.05]）,且感染2周组小鼠TLR2和TLR4蛋白较感染1周组小鼠的表达量明显增高 （P均[<0.05]）。结论 TLR2和TLR4参与了肠黏膜对微小隐孢子虫的识别,感染导致的肠黏膜损伤可能与其上调TLR2和TLR4表达相关。     

Mechanisms of innate and acquired resistance to Cryptosporidium parvum infection in SCID mice

SCID mice, which lack T and B cells, were used as hosts to investigate the nature of both T cell-independent and T-cell-dependent immune responses to infection with Cryptosporidium parvum. We found previously that SCID mice developed chronic infections in which the level of oocyst excretion was low up to about eight weeks post-infection but then increased significantly to cause morbidity and death after 13 weeks. In the present study, weekly administration of an anti-IFN-γ monoclonal antibody (MoAb) resulted in a shortened prepatent time, significant increase in oocyst excretion and early onset of disease and death. These results suggested an immunologically mediated resistance to C. parvum in the SCID host which required the production of IFN-γ. Attempts to demonstrate a role for TNF in nonspecific immunity were unsuccessful as injection of mice at weekly intervals with an anti-TNF MoAb failed to alter the course of infection. In contrast to the chronic infection observed in the mice above, SCID mice reconstituted with spleen cells from naïve BALB/c mice were able to recover. Depletion of CD4⁺ cells from the donor population abrogated this protective effect. Mice receiving spleen cells depleted of CD8⁺ cells were able to recover but the patent infection was prolonged compared with those obtained in mice receiving unfractionated cells. These results demonstrate that CD4⁺ cells are necessary for the development of immunity to C. parvum infection in reconstituted SCID mice, but, in addition, that CD8⁺ cells also make a significant contribution to this immunity.     

Mucosal cytokine and antigen-specific responses to Cryptosporidium parvum in IL-12p40 KO mice

Studies of cellular immune responses to Cryptosporidium parvum have been limited in part by lack of suitable animal models. IL-12p40(-/-)mice are susceptible to initial infection with C. parvum but recover within 2 weeks, rendering the animals resistant to reinfection. Because the host responses that determine duration and severity of primary infection are not yet understood, we studied the cellular immune response to primary infection with C. parvum in IL-12p40(-/-)mice and also explored possible mechanisms for this response. Female IL-12p40(-/-)mice were inoculated with 10,000 oocysts. Uninfected age-matched mice served as controls. At different time intervals following exposure to oocysts, mice were sacrificed and their intestine, spleen, and mesenteric lymph node tissues were harvested. Cellular immune responses to C. parvum were characterized. Infection of IL-12p40(-/-)mice induced changes in the gene expression of the cytokines IFN-gamma, IL-4, IL-15, IL-18, TNF-alpha and TGF-beta during primary infection. There was also a significant increase in total numbers of lymphocytes and CD19/CD62L-expressing cells in mesenteric lymph nodes. These MLN cells exhibited increased antigen-specific proliferation and cytokine production (IL-6 and IFN-gamma) levels when stimulated in vitro. These observations delineate the cellular immune responses during acute C. parvum infection of the IL-12p40(-/-)mouse model.     

微小隐孢子虫LDH基因的克隆与序列分析

目的克隆微小隐孢子虫(Cryptosporidium parvum,Cp)南京株(NJ)乳酸脱氢酶(lactate dehydrogenase,LDH)基因,测序并分析微小隐孢子虫NJ株CpLDH与其他隐孢子虫分离株LDH基因序列的差异。方法根据微小隐孢子虫已知LDH 基因序列设计合成2对引物, 应用巢式PCR 技术从微小隐孢子虫NJ株基因组DNA 中扩增LDH 基因, 并将其克隆到pMD18 T 载体上,阳性克隆的重组质粒经PCR及双酶切鉴定后, 用双脱氧链终止法对重组质粒中的插入序列进行测序,应用生物信息学方法分析 CpLDH 基因序列和其他物种LDH序列的同源性。结果巢式PCR 扩增得到特异的CpLDH 基因序列,经PCR及双酶切鉴定获得了正确的pMD18 T CpLDH 重组质粒。测序表明, NJ株微小隐孢子虫LDH 基因全长966 bp, 编码322个氨基酸,该基因序列已登录GenBank,登录号为 HM001298。序列分析表明, 我国微小隐孢子虫NJ株与国外分离的Iowa II株 LDH基因编码的氨基酸序列具有98%的同源性。结论成功克隆了微小隐孢子虫NJ株LDH 基因;序列测定及同源性分析表明, 微小隐孢子虫NJ株在LDH酶关键结构位点存在突变。     

微小隐孢子虫卵囊DNA提取及用于PCR检测

目的采用3种方法提取微小隐孢子虫卵囊DNA,并用于PCR检测以进行比较。方法 微小隐孢子虫卵囊经多次冻融加热破壁后,采用螯合树脂(Chelex-100)、酚/氯仿和基因组DNA纯化系统试剂盒3种方法提取微小隐孢子虫卵囊DNA,并根据微小隐孢子虫基因序列(L16996)设计一对寡核苷酸引物,分别对3种方法制备模板进行PCR扩增分析。Chelex-100提取的DNA也用于观察PCR检测的敏感性。结果3种方法制备的微小隐孢子虫卵囊模板用于PCR检测均获得1条446 bp条带,Chelex-100提取的DNA用于PCR检测的敏感性至少达0.5个卵囊。结论3种方法提取的微小隐孢子虫卵囊DNA均可用于PCR检测,Chelex-100法是一种高效而快速的微量提取DNA方法,适用于对隐孢子虫DNA的检测。     

Genetic immunization in the lung induces potent local and systemic immune responses

Successful vaccination against respiratory infections requires elicitation of high levels of potent and durable humoral and cellular responses in the lower airways. To accomplish this goal, we used a fine aerosol that targets the entire lung surface through normal respiration to deliver replication-incompetent recombinant adenoviral vectors expressing gene products from several infectious pathogens. We show that this regimen induced remarkably high and stable lung T-cell responses in nonhuman primates and that it also generated systemic and respiratory tract humoral responses of both IgA and IgG isotypes. Moreover, strong immunogenicity was achieved even in animals with preexisting antiadenoviral immunity, overcoming a critical hurdle to the use of these vectors in humans, who commonly are immune to adenoviruses. The immunogenicity profile elicited with this regimen, which is distinct from either intramuscular or intranasal delivery, has highly desirable properties for protection against respiratory pathogens. We show that it can be used repeatedly to generate mucosal humoral, CD4, and CD8 T-cell responses and as such may be applicable to other mucosally transmitted pathogens such as HIV. Indeed, in a lethal challenge model, we show that aerosolized recombinant adenoviral immunization completely protects ferrets against H5N1 highly pathogenic avian influenza virus. Thus, genetic immunization in the lung offers a powerful platform approach to generating protective immune responses against respiratory pathogens.     

STAg和CT滴鼻免疫小鼠诱导的刚地弓形虫特异性黏膜及系统免疫应答

刚地弓形虫（Toxoplasma gondii）属专性细胞内寄生性原虫，人群感染极为普遍，全球约20亿人感染，2001—2004年中国人群血清阳性率高达7．88％。弓形虫感染在免疫缺陷、免疫抑制者可引起严重病变，孕期感染可经胎盘垂直传播致先天性弓形虫病。研制安全、有效、价廉的疫苗防治弓形虫感染乃当务之急。机体95％以上的感染发生在黏膜部位，皮下、肌肉接种疫苗不能有效诱导黏膜部位的免疫应答，只有从黏膜部位进行疫苗接种，才能有效预防黏膜感染。     

微小隐孢子虫种特异性基因片段的克隆及诊断引物的确定

目的　寻找用于诊断微小隐孢子虫病的特异性引物。　方法　在RAPD分析过程中获得了 1条微小隐孢子虫 [Cryptosporidium parvum (C .parvum ) ]种特有 712bp的基因片段 ,将该片段分离、纯化、克隆和测序 ,据此序列合成一对特异性引物FF。用引物FF扩增美国 2株C .parvum和中国 4株C .parvum ,并用该引物与Morgan( 1996 )发表的C .parvum种特异性诊断引物 0 2 1作对照 ,检测镜检C .parvum卵囊阴性的兔粪样 35份和人粪样 5 5份。　 结果　引物FF扩增 6株C .parvum均能产生预计 6 0 3bp的片段 ,引物FF和引物 0 2 1粪样检测结果完全一致 ,其敏感性是可检出 1个卵囊的DNA。　结论　获得的引物FF特异性强 ,敏感性高 ,可用于微小隐孢子虫病的诊断。     

微小隐孢子虫病毒衣壳蛋白的原核表达及鉴定

目的对微小隐孢子虫病毒衣壳蛋白S-dsRNA基因进行克隆、表达和反应原性分析。方法以微小隐孢子虫总RNA逆转录的cDNA为模板,克隆S-dsRNA基因,并转化至原核表达载体pET-28a(+)中,构建重组原核表达载体pET-28a(+)-S,转入大肠埃希菌BL21(DE3)中,用异丙基-β-D-硫代半乳糖苷(IPTG)诱导表达,十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)观察重组蛋白的表达情况,蛋白质印迹(Western blotting)分析重组蛋白与鼠抗微小隐孢子虫阳性血清的反应原性。结果 PCR和双酶切鉴定表明,重组质粒pET-28a(+)-S构建成功。SDS-PAGE结果显示,37℃下经1mmol/L IPTG诱导4h,重组蛋白表达量最大。重组蛋白主要以包涵体形式表达,相对分子质量(Mr)约为37000,与预期大小一致,重组蛋白约占蛋白总量的72.6%。Western blotting分析结果表明,重组蛋白能识别抗微小隐孢子虫阳性鼠血清。结论微小隐孢子虫病毒衣壳蛋白S-dsRNA基因表达成功,重组蛋白具有反应原性。     

微小隐孢子虫感染犬肾细胞模型的建立及生长发育过程的研究

目的 建立微小隐孢子虫体外感染犬肾细胞（MDCK细胞）模型, 并观察其生长发育过程。 方法 利用MDCK细胞为隐孢子虫感染对象, 优化隐孢子虫感染MDCK细胞的培养条件, 观察隐孢子虫在MDCK细胞中的生长发育过程。将体外感染48 h的细胞培养上清接种小鼠, 观察其感染情况。 结果 在含有5%胎牛血清的DMEM培养基中, 用1×10⁵隐孢子虫卵囊感染2.0×10⁵个MDCK细胞, 培养12 h为最佳培养条件。在感染后72 h内, 隐孢子虫出现连续发育阶段, 包括脱囊、子孢子、裂殖子、裂殖体、滋养体、配子体、合子、薄壁卵囊和厚壁卵囊, 在60～72 h内形成卵囊;用感染48 h的细胞培养上清接种于免疫抑制小鼠, 10 d后有隐孢子虫卵囊排出。 结论 建立了能稳定用于微小隐孢子虫体外感染的MDCK细胞模型, 观察到隐孢子虫的生长发育全过程。     

构建检测隐孢子虫特异性抗体的多重微粒子免疫检测法

目的 建立一种检测微小隐孢子虫特异性抗体的微粒子免疫检测法(MIA).方法 以纯化的重组蛋白CP23、SA35和SA40为检测抗原,以牛血清白蛋白(BSA)为内参,偶联微粒子,并进行蛋白偶联效率验证.比较单一MIA法和多重MIA法的一致性,以及多重MIA法检测的板内和板间差异.结果 纯化蛋白和BSA成功偶联到相应的微粒...     

Kinetics of spleen and Peyer's patch lymphocyte populations during gut parasite clearing in Cryptosporidium parvum infected suckling mice

Data from experimental and human cryptosporidiosis have established a major role of specific immunity in the control of Cryptosporidium parvum infection. In this work, alterations in spleen and Peyer's patch (Pp) lymphocytes were investigated in the course of a spontaneously resolutive gut cryptosporidiosis in four-day-old suckling NMRI mice infected with either 4 x 10(5) or 30 viable oocysts. Oocysts from entire small intestines, and spleen and Pp lymphocytes were examined using flow cytometry from day 7 to day 27 post-infection. Compared to uninfected animals, a 3-5 fold increase in the numbers of spleen TCR alphabeta+, CD4+, CD8+, TCR gammadelta+ and CD45R/B220+ lymphocytes was observed on day 17 post-infection in heavily infected animals. In Pp, more than ten-fold increases were observed, except for TCR gammadelta+ lymphocytes. At termination of infection, i.e. on days 21-23 after ingestion of 4 x 105 oocysts, T and B lymphocytes decreased rapidly in both organs, and remained lower than in uninfected animals on days 19-23 post-infection. In mice infected with 30 oocysts, similar alterations were observed in Pp, but not in spleen. Data suggest that in normally developing mice, clearance of gut C. parvum infection is associated with an initial increase in systemic and local lymphocyte numbers, followed by their decrease to below control levels during the recovery phase.     

微小隐孢子虫重组BCG-Cp23疫苗的构建及鉴定

目的构建和鉴定微小隐孢子虫Cp23基因卡介苗重组疫苗。方法用微小隐孢子虫感染免疫抑制BALB/c小鼠,用蔗糖密度梯度离心法纯化其粪便中的卵囊,酚-氯仿法提取微小隐孢子虫的基因组DNA,PCR扩增Cp23基因片段,然后将其克隆TA载体;通过酶切、测序鉴定后,将Cp23基因片段用限制性内切酶切下克隆至大肠埃希菌-分枝杆菌穿梭表达载体pMV262结核杆菌热休克蛋白(HSP)启动子下游,构建重组质粒pMV262-Cp-23,用电穿孔将该质粒导入野生卡介苗(BCG-WT)构建微小隐孢子虫Cp23基因卡介苗重组疫苗。结果扩增出约360bp的微小隐孢子虫Cp23基因片段并成功构建pMV262-Cp23质粒,通过PCR扩增和提取质粒、酶切表明质粒正确导入BCG-WT中。结论成功构建微小隐孢子虫Cp23基因卡介苗重组疫苗。     

Humoral immune response in IL-12 and IFN-gamma deficient mice after infection with Cryptosporidium parvum

Infection with Cryptosporidium spp. causes diarrhoeal disease and has become an important medical and veterinary problem especially in the immunocompromised host. The importance of the adaptive immune response, with CD4+ T-lymphocytes being the major players, has been clearly demonstrated. The requirement of IL-12 and IFN-gamma identifies this response as a Th1-dominated reaction. IFN-gamma is also important in the early phase of the host-parasite interaction. We analysed the outcome of infection in IL-12p40 (IL-12KO) and IFN-gamma (GKO) deficient C57BL/6 mice after primary and secondary challenge with the parasite and, for the first time, we demonstrate the resulting Ig response in sera and vaginal lavages. Although showing differences in the extent and the time course both strains of mice were able to clear infection and developed an almost complete resistance to re-infection. While GKO mice mounted prolonged parasite-specific IgG and IgA responses after primary infection, in IL-12KO mice IgG and IgA titres dropped over time. Re-challenge of mice 5 weeks after primary infection led to a booster effect in Ig response despite the absence of oocyst shedding. The data from infection and re-challenge experiments suggest that in IL-12- or IFN-gamma-deficient mice the development of resistance involves other protective immune responses.     

微小隐孢子虫cDNA文库的构建及P23、CP15/60基因的克隆

目的　微小隐孢子虫地方株cDNA文库构建及P2 3、CP15 60基因的克隆。　方法　提取微小隐孢子虫总RNA、mRNA ,逆转录合成cDNA。将cDNA与 pUC18DNA连接 ,导入DH5α宿主细胞中生成cDNA文库。根据文献分别设计并合成两对PCR引物 ,从上述文库中筛选保护性基因 ,对PCR产物克隆、测序。　结果　文库容量为 1.9× 10 6个重组子 ,文库中cDNA插入片段大小介于 0 .4× 10 3～ 6.5× 10 3bp。从该文库中克隆出编码 2 3kDa、15 60kDa子孢子表面蛋白的核苷酸序列。　结论　成功地用 pUC18质粒载体构建了C .parvumcDNA文库。