A component of an antigenic rhoptry complex of Plasmodium falciparum is modified after merozoite invasion

Human antibodies affinity purified on an adsorbent prepared from a cDNA clone (Ag44) expressing a portion of a rhoptry antigen were used to characterize the synthesis and fate of the antigen in the asexual blood stages of Plasmodium falcipartum. The rhoptry antigen is synthesized in the mature trophozoite-stage parasites as a 103 kDa polypeptide, is present in the schizonts and merozoites as a 105 kDa polypeptide, is discharged from the rhoptries and found in the newly invaded red cells as a 110 kDa polypeptide. Anti-Ag44 antibodies immunoprecipitate the antigen and two additional polypeptides of 135 and 150 kDa from lysates of infected cells and from culture supernatants. The three polypeptides are associated in a non-covalent complex that persists in the newly invaded red cells. All the components of the high molecular weight rhoptry complex are antigenic and can be precipitated with immune human serum. The 135 kDa polypeptide is identical to a 140 kDa rhoptry antigen previously identified by a monoclonal antibody.     

弓形虫ROP2基因的克隆及在大肠杆菌中的表达

目的 :构建弓形虫棒状体蛋白 (ROP2 )基因重组质粒并在大肠杆菌中表达 ,用于筛选弓形虫新的诊断抗原和疫苗分子。方法 :根据ROP2基因已知序列 ,设计合成一对引物 ,用PCR方法从弓形虫RH株基因组DNA中扩增出ROP2基因片段 ,再克隆到pGEX 4T 1质粒 ,重组质粒经酶切及PCR鉴定 ,而后进行测序 ;重组质粒在大肠杆菌BL2 1 (DE3)中进行ITPG诱导表达 ,表达产物经SDS PAGE及WesternBlot分析。结果 :ROP2基因PCR产物大小与预期相符 ,约 1 0 4 3bp ,重组质粒经酶切及PCR鉴定表明获得正确重组子 ,测序结果与已知序列基本吻合 ;SDS PAGE及免疫印迹显示ROP2融合蛋白表观分子量约为 5 5kDa ,表达产物约占菌体总蛋白1 7% ,具有一定的免疫反应性。结论 :克隆并表达了弓形虫ROP2基因 ,为下一步弓形虫诊断及疫苗研究奠定了基础     

Antibodies to the Plasmodium falciparum rhoptry protein RAP-2/RSP-2 in relation to anaemia in Cameroonian children

Previous studies have implicated reactive antibodies to the low molecular weight rhoptry‐associated proteins (RAP‐1, RAP‐2/RSP‐2 and RAP‐3) in erythroid cell destruction during Plasmodium falciparum infection. In this pilot study, the frequency, specificity and functional capacity of naturally acquired anti‐RAP‐2/RSP‐2 antibodies were investigated in the sera of anaemic and nonanaemic malaria‐infected Cameroonian children. All sera recognized RAP‐2/RSP‐2 by FACS, irrespective of the clinical status of the subjects. However, the anaemic children showed higher levels of IgG antibodies than the nonanaemic group, while both groups showed similar levels of IgM antibodies. Only few individuals had detectable levels of RAP‐2/RSP‐2‐specific IgG1 and IgG3 subclass antibodies, while no IgG2 and IgG4 subclass antibodies were detected in these subjects. By ELISA, the anaemic group tended to show higher levels of antibodies to RAP‐2/RSP‐2 regarding all antibody classes tested, except for IgG4 and IgE. Unexpectedly, sera from the nonanaemic group activated complement to a greater extent than those from the anaemic group. These results need to be confirmed in extended studies but indicate that the effector functions of the RAP‐2/RSP‐2‐reactive antibodies may be more important than their amounts. Such antibodies could play a role in both immunity and pathogenesis during P. falciparum infection.     

编码弓形虫ROP1蛋白基因的体外扩增、克隆及在E.coli中的表达

目的构建弓形虫棒状体蛋白（ＲＯＰ１）基因重组质粒并在Ｅ．ｃｏｌｉ中表达。方法用ＲＨ株接种小鼠,收集腹水,纯化速殖子,抽提基因组ＤＮＡ;据ＲＯＰ１基因序列设计合成一对引物,将上、下游引物分别引入ＥｃｏＲＩ,ＢａｍＨＩ酶切位点,用ＰＣＲ技术从ＲＨ株基因组ＤＮＡ中扩增编码ＲＯＰ１的基因片段,插入ｐＢＶ２２０质粒,转化大肠杆菌ＤＨ５α感受态细胞,于氨苄阳性ＬＢ培养平板上筛选阳性克隆,酶切鉴定;经温度诱导在Ｅ．ｃｏｌｉ中表达,ＳＤＳ－ＰＡＧＥ及免疫印迹分析。结果ＲＯＰ１基因体外扩增产物大小与预期值相符,约７５６ｂｐ;构建成功ｐＢＶ２２０－ＲＯＰ１重组质粒;ＳＤＳ－ＰＡＧＥ、免疫印迹显示特异蛋白条带的分子量约４３ｋＤ,表达产量约占菌体蛋白１３．２３％。结论从弓形虫基因组ＤＮＡ中获取ＲＯＰ１基因,并成功构建ｐＢＶ２２０－ＲＯＰ１重组质粒,诱导表达ＲＯＰ１非融合蛋白,为进一步分离纯化、用于对弓形虫侵入机制及免疫特性的研究做好准备。     

含弓形虫ROP1基因真核表达重组质粒DNA免疫小鼠的研究 IV.免疫鼠血清细胞因子IFN-γ、IL-2及NO的测定

目的　用 pc- ROP1重组质粒免疫小鼠 ,观察其对细胞因子 IFN-γ、IL - 2及 NO的影响。方法　碱裂解法大量制备 pc- ROP1质粒 DNA,经肌肉注射免疫 BAL B/ c小鼠 ,每只鼠注射 10 0μg,两周后同量加强免疫一次 ,以 pc DNA 3空质粒及生理盐水组为对照。分别于免疫后第 30天、5 0天、70天共三次用双夹心 EL ISA测定血清细胞因子 IFN-γ、IL - 2含量 ;酶法测定NO活性。结果　三次检测免疫组 IFN-γ、IL - 2及 NO含量均显著高于对照组 ,随着免疫时间的延长有增高趋势。结论　 pc-ROP1重组质粒 DNA免疫小鼠 ,可刺激细胞因子 IFN-γ、IL - 2产生 ,NO分子的释放     

弓形虫多基因核酸疫苗构建及其免疫保护性研究

目的 构建弓形虫多基因核酸疫苗, 评价其免疫保护性。方法 PCR扩增热休克蛋白 （HSP70） 基因片段, 克隆到 pcDNA3?ROP2?p30重组质粒中, 构建pcDNA3?ROP2?p30?HSP70多基因核酸疫苗。采用该疫苗免疫BALB/c小鼠, 检测小鼠脾淋巴细胞及全血CD4+ 、 CD8+ , 血清、 脾淋巴细胞培养液中IgG、 IgM、 IgA和IFN?γ、 TNF、 IL?2、 IL?4、 IL?12等, 并进行弓形虫攻击感染实验。结果 应用PCR扩增出916 bp HSP70基因片段, 成功构建pcDNA3?ROP2?p30?HSP70重组体, 其中包含 HSP70 蛋白基因读码框内的完整序列。该弓形虫多基因核酸疫苗能诱发小鼠产生细胞免疫和体液免疫, 实验组小鼠血清抗体滴度高, CD4+ 和 CD8+ 均增殖明显, 组间差异有统计学意义（FCD4+ =45.00, FCD8+ =15.01, P均＜0.01）; 其血清及脾细胞培养液中IFN?γ、 IL?2和IL?12含量均明显升高, 尤以血清中升高显著。攻击实验结果显示, 实验组小鼠存活时间明显延长。结论 pcDNA3?ROP2?p30?HSP70多基因核酸疫苗具有较强的免疫原性, 能产生较好的免疫保护作用。     

巴贝虫棒状体蛋白的研究进展

巴贝虫是一类专性的细胞内寄生的顶复门原虫,是人和动物的重要病原。这类原虫具有相似的亚细胞结构并能分泌与入侵相关的保守蛋白,尤其是在入侵宿主细胞阶段分泌的棒状体相关蛋白被认为是保护寄生虫入侵和繁殖的关键分子,其在虫体入侵的纳虫空泡形成过程中发挥重要作用。随着基因组学和蛋白质组学技术的不断发展,其相关研究也越来越深入。因此,本文就目前研究较多的牛巴贝虫、羊巴贝虫、吉氏巴贝虫、双芽巴贝虫和东方巴贝虫等棒状体相关蛋白的研究现状进行了综述。     

弓形虫棒状体蛋白的免疫原性及其DNA疫苗的研制

目的研制抗弓形虫DNA疫苗,评价其免疫原性及免疫保护作用,进而推广应用。方法首先用RH株弓形虫速殖子提取基因组DNA,应用PCR、酶切、连接、测序等技术,扩增棒状体蛋白2（ROP2）基因片段,将其克隆于真核表达载体pc-DNA3质粒中,制备抗弓形虫棒状体蛋白2DNA疫苗。再应用该疫苗免疫小鼠,取其血清、脾和淋巴结培养液检测免疫学指标评价其免疫原性,最后应用弓形虫攻击感染实验评价其免疫保护作用。结果PCR扩增出1.7kb ROP2基因片段,克隆、构建出pc-DNA3-ROP2重组DNA疫苗能诱发小鼠产生强烈的细胞免疫和体液免疫反应,小鼠血清抗体滴度高且能正确识别由基因重组体外诱导表达的ROP2蛋白抗原;实验组小鼠CD4^＋T细胞增殖明显,体液中各细胞因子含量均有不同程度的升高,尤其是血清中升高最为显著。弓形虫攻击感染180h后,疫苗免疫保护率为88.9％,小鼠存活时间明显延长。结论pc-DNA3-ROP2重组DNA疫苗具有较强的免疫原性,安全可靠,能产生良好的免疫保护作用。     

Multiple genes code for high-molecular-mass rhoptry proteins of Plasmodium yoelii

We have examined the number of genes coding for a group of high-molecular-mass rhoptry protein(s) in the malaria parasite Plasmodium yoelii, and studied variation in the gene family within the parasite's genome. A region of the genes was amplified using oligonucleotides based on conserved DNA sequences and the products cloned. The sequences could be divided into 7 groups by restriction-fragment-length polymorphism. Further variation was detected by sequence analysis; 11 different sequences were detected in the 16 clones analyzed. The genes in the family were distributed on 6 chromosomes probably at 9 or more loci.     

Isolation of a Plasmodium falciparum rhoptry protein

A monoclonal antibody raised against the malaria parasite Plasmodium falciparum recognised a protein of 140000 molecular weight which was synthesized during schizogony. The protein has been purified by monoclonal antibody affinity chromatography from extracts of parasitized red cells. Antibodies against the protein have been used to determine its subcellular location. The protein is not expressed on the merozoite surface and has been located in the rhoptries, the apical organelles of the merozoite.