恶性疟原虫疫苗研究X.MSP1中类表皮生长因子1与PfCMR基因？…

目的 克隆并表达恶性疟原虫重组复合抗原，为疟疾疫苗研究奠定基础。方法 将恶性疟原虫ＭＳＰ１中类表皮生长因子１（ＥＧＦ－１）基因与人工化学合成的抗原复合基因ＰｆＣＭＲ串接，插入高效非融合型蛋白表达载体ｐＢＶ２２０，转化大肠杆菌ＤＨ５ａ，转化菌经４２℃热诱导表达，表达产物用Ｗｅｓｔｅｒｎ ｂｌｏｔ和Ｄｏｔ－ＥＬＩＳＡ分析。结果 构建成功重组质粒ｐＢＶ２２０／ＰｆＣＭＲ－ＥＧＦ－１，经热诱导后表达出含外     

检测血清和脑脊液中囊尾蚴循环抗原诊断脑囊虫 …

目的：用抗血清检测脑囊虫病患者血清和脑脊液（ＣＳＦ）中囊尾蚴循环抗原（ＣＡｇ）诊断脑囊虫病。方法：用ＳＤＳ－ＰＡＧＥ提纯的蛋白质分子量为６４ｋＤａ、５３ｋＤａ、３２ｋＤａ～３０ｋＤａ的囊尾蚴抗原分别免疫家兔,制备相应的抗血清,以双夹心ＥＬＩＳＡ 检测患者血清和ＣＳＦ中ＣＡｇ。结果：抗原体５３ｋＤａ抗原抗血清对３２例脑囊虫病活动型患者血清和ＣＳＦ中ＣＡｇ的检出率分别为９３．８％和９１．７％,１６例脑     

McAb4F8、McAb1F11与囊尾蚴抗原作用免疫印渍分析

将猪囊尾蚴囊液抗原（ＣＣＦＡ）和脑囊虫病病人脑脊液（ＰＣＳＦ）进行ＳＤＳ－ＰＡＧＥ电泳分析，发现在ＣＣＦＡ中有１４条蛋白带，范围在２８～７６ｋＤａ。脑囊虫病病人ＣＳＦ中有６条蛋白带，范围在３３～８３ｋＤａ。用ＣＣＦＡ和ＰＣＳＦ与ＭｃＡｂ４Ｆ８和ＭｃＡｂ１ＦＩ１１免疫印迹试验，证明ＣＣＦＡ中５０、５３、６３和７０ｋＤａ蛋白带与两株ＭｃＡｂ均有反应，另一条蛋白带３３ｋＤａ仅能被ＭｃＡｂ１Ｆ１１识别。ＰＣＳＦ中的６条蛋白带中有３条（５３，６３和７０ｋＤａ）与２株ＭｃＡｂ均有反应，另一条蛋白带３３ｋＤａ仅与ＭｃＡｂ１Ｆ１１反应。２例对照脑脊液中未出现反应带。结果显示ＭｃＡｂ４Ｆ８和ＭｃＡｂ１Ｆ１１均抗ＣＣＦＡ和ＰＣＳＦ中的主要蛋白带。     

检测血清和脑脊液中囊尾蚴循环抗原诊断脑囊虫病的研究

目的：用抗血清检测脑囊虫病患者血清和脑脊液（ Ｃ Ｓ Ｆ）中囊尾蚴循环抗原（ Ｃ Ａｇ）诊断脑囊虫病。方法：用 Ｓ Ｄ Ｓ Ｐ Ａ Ｇ Ｅ提纯的蛋白质分子量为 ６４ ｋ Ｄａ、５３ ｋ Ｄａ、３２ ｋ Ｄａ～３０ ｋ Ｄａ 的囊尾蚴抗原分别免疫家兔,制备相应的抗血清,以双夹心 Ｅ Ｌ Ｉ Ｓ Ａ 检测患者血清和 Ｃ Ｓ Ｆ中 Ｃ Ａｇ。结果：抗５３ ｋ Ｄａ 抗原抗血清对 ３２ 例脑囊虫病活动型患者血清和 Ｃ Ｓ Ｆ中 Ｃ Ａｇ 的检出率分别为９３．８％ 和９１．７％ ,１６ 例脑囊虫病非活动型患者仅１ 例 Ｃ Ｓ Ｆ Ｃ Ａｇ 阳性。 Ｃ Ａｇ 检出率明显高于用抗６４ ｋ Ｄａ、３２ ｋ Ｄａ～３０ ｋ Ｄａ 囊尾蚴抗原抗血清检测的结果（ Ｐ＜ ０．０５）。结论：抗５３ ｋ Ｄａ 囊尾蚴抗原抗血清检测活动型脑囊虫病患者血清和 Ｃ Ｓ Ｆ中的 Ｃ Ａｇ 敏感性较高,特异性较强,可用于活动型脑囊虫病的诊断和疗效考核。     

McAb4F8,McAb1F11与囊尾蚴抗原作用免疫印渍分析

将猪囊尾蚴囊液抗原（ＣＣＦＡ）和脑囊虫病病人脑脊液（ＰＣＳＦ）进行ＳＤＳ－ＰＡＧＥ电泳分析，发现在ＣＣＦＡ中有１４条蛋白带，范围在２８～７６ｋＤａ。脑囊虫病病人ＣＳＦ中有６条蛋白整，范围在３３～８３ｋＤａ。用ＣＣＦＡ和ＰＣＳＦ与ＭｃＡｂ４Ｆ     

日本血吸虫与华支睾吸虫和姜片虫之间的交叉抗原及其血清学反应性

应用ＳＤＳ－ＰＡＧＥ分离ＡＷＡ、ＣＳＡ和ＦＳＡ三种抗原的组分蛋白后，再以酶联免疫印迹技术（ＥＬＩＢ）进一步鉴定其组分蛋白的特异性蛋白带，分别显示１２条、１９条和２１条，其分子量（ＭＷ）范围分别为１３～６４ｋＤｅ、１６～１９８．５ｋＤａ和１４～１５０ｋＤａ。ＡＷＡ组分蛋白与兔抗ＳＥＡ免疫血清出现３条交叉反应带．ＭＷ为１７ｋＤａ、１４ｋＤａ和１３ｋＤａ，与抗ＣＳＡ的兔血清及华支睾吸虫病人血清显示３条（３８ｋＤａ、１７．５ｋＤａ及１７ｋＤｅ）交叉反应带．与抗ＦＳＡ的兔血清及姜片虫病人血清呈现５条（６４ｋＤａ、５９ｋＤｅ、５３ｋＤｅ、１７．５ｋＤａ和１７ｋＤａ）交叉反应带。实验结果表明，日本血吸虫成虫不仅与其虫卵之间存有交叉抗原，而且与华支睾吸虫和姜片虫成虫之间也存有交叉抗原及血清学交叉反应性。本研究为今后制备特异的血吸虫病血清学诊断抗原，提供了科学依据。     

系统性红斑狼疮患者淋巴细胞粘附分子表达的观察

用流式细胞术及免疫双荧光染色法，分析了３５例系统性红斑狼疮（ＳＬＥ）患者外周血淋巴细胞粘附分子表型（ＣＤ＿（１１ａ）／ＬＦＡ－ｌα、ＣＤ＿（１８）／ＬＦＡ－１β、ＣＤ＿（５４）／ＩＣＡＭ－１）。结合淋巴细胞变化对ＳＬＥ作进一步探讨。结果发现ＳＬＥ活动期ＣＤ＿（１１ａ）、ＣＤ＿（１８）表达随ＣＤ＿４细胞减少而降低、ＣＤ＿８细胞增多而增高，ＣＤ＿（５４）在ＣＤ＿（２０）细胞上亦增高。此外，ＣＤ＿８细胞的ＣＤ＿（１８）增高与ＣＤ＿４ＣＤ＿（４５）ＲＡ￣＋细胞降低呈负相关（Ｐ＜０．０５），而与ＣＤ＿（２０）细胞的ＣＤ＿（５４）增高呈正相关（Ｐ＜０．０１）。提示粘附分子可能在ＳＬＥ发病机理中具有重要意义。     

恶性疟原虫环子孢子蛋白基因在大肠杆菌中的表达

用ＰＣＲ方法特异性扩增恶性疟原虫云南株（ＰＦＤ－３／ＹＮ）环子孢子蛋白基因片段,经基因序列测定后克隆于ｐＷＲ４５０－１融合蛋白表达载体,并转化大肠杆菌ＴＧ１、ＪＭ１０３及ＪＭ１０９。在不同菌体浓度及不同剂量ＩＰＴＧ诱导下检测ＣＳＰ融合蛋白的表达,结果显示仅ｐＷＲ－ＣＳＰ／ＴＧ１工程菌在菌体浓度ＯＤ５９０值达０．７～０．８时,加入终浓度１ｍｍｏｌ／ＬＩＰＴＧ进行诱导,可表达一８８ｋＤａ的融合蛋白。ｄｏｔ－ＥＬＩＳＡ和Ｗｅｓｔｅｒｎｂｌｏｔ分析表明ＣＳ蛋白表达产物能被抗ＣＳ蛋白重复区单克隆抗体所识别     

马来丝虫病特异性诊断抗原研究

采用ＳＤＳ－ＰＡＧＥ和ＥＬＩＢ技术分析马来丝虫成虫（ＭＡＡ）和微丝蚴（ＭＦＡ）可溶性抗原。马来丝虫成虫和微丝蚴采自感染沙鼠腹腔。分析结果表明，ＭＦＡ蛋白组分含有沙鼠腹腔液蛋白组分（６４－６７ｋＤａ和５６－５８ｋＤａ）。健康沙鼠血清与ＭＦＡ作ＥＬＩＢ，可见３条淡反应带（６０ｋＤａ、７４ｋＤａ和１００ｋＤａ），与ＭＡＡ无反应带可见。ＭＡＡ蛋白组分中的４２ｋＤａ和１４．５ｋＤａ可被感染６个月的阳性沙鼠血清识别，而不被阴性沙鼠血清识别。     

哮喘患者细胞粘附分子表达及血浆可溶性E-选择素、P-选择素含量变化研究

哮喘患者细胞粘附分子表达及血浆可溶性Ｅ－选择素、Ｐ－选择素含量变化研究张波刘树芬张劭夫齐法莲孙文杰细胞粘附分子与哮喘气道粘膜炎性细胞浸润有密切关系［１］，本组对哮喘患者外周血单个核细胞（ＰＢＭＣｓ）表面的ＣＤ１１ａ／ＣＤ１８（淋巴细胞功能相关抗原－１...     

Evasion of immunity to Plasmodium falciparum malaria by IgM masking of protective IgG epitopes in infected erythrocyte surface-exposed PfEMP1

Plasmodium falciparum malaria is a major cause of mortality and severe morbidity. Its virulence is related to the parasite's ability to evade host immunity through clonal antigenic variation and tissue-specific adhesion of infected erythrocytes (IEs). The P. falciparum erythrocyte membrane protein 1 (PfEMP1) family is central to both. Here, we present evidence of a P. falciparum evasion mechanism not previously documented: the masking of PfEMP1-specific IgG epitopes by nonspecific IgM. Nonspecific IgM binding to erythrocytes infected by parasites expressing the PfEMP1 protein VAR2CSA (involved in placental malaria pathogenesis and protective immunity) blocked subsequent specific binding of human monoclonal IgG to the Duffy binding-like (DBL) domains DBL3X and DBL5ε of this PfEMP1 variant. Strikingly, a VAR2CSA-specific monoclonal antibody that binds outside these domains and can inhibit IE adhesion to the specific VAR2CSA receptor chondroitin sulfate A was unaffected. Nonspecific IgM binding protected the parasites from FcγR-dependent phagocytosis of VAR2CSA(+) IEs, but it did not affect IE adhesion to chondroitin sulfate A or lead to C1q deposition on IEs. Taken together, our results indicate that the VAR2CSA affinity for nonspecific IgM has evolved to allow placenta-sequestering P. falciparum to evade acquired protective immunity without compromising VAR2CSA function or increasing IE susceptibility to complement-mediated lysis. Furthermore, functionally important PfEMP1 epitopes not prone to IgM masking are likely to be particularly important targets of acquired protective immunity to P. falciparum malaria.     

Identification of a Plasmodium falciparum intercellular adhesion molecule-1 binding domain: a parasite adhesion trait implicated in cerebral malaria

Binding of infected erythrocytes to brain venules is a central pathogenic event in the lethal malaria disease complication, cerebral malaria. The only parasite adhesion trait linked to cerebral sequestration is binding to intercellular adhesion molecule-1 (ICAM-1). In this report, we show that Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) binds ICAM-1. We have cloned and expressed PfEMP1 recombinant proteins from the A4tres parasite. Using heterologous expression in mammalian cells, the minimal ICAM-1 binding domain was a complex domain consisting of the second Duffy binding-like (DBL) domain and the C2 domain. Constructs that contained either domain alone did not bind ICAM-1. Based on phylogenetic criteria, there are five distinct PfEMP1 DBL types designated alpha, beta, gamma, delta, and epsilon. The DBL domain from the A4tres that binds ICAM-1 is DBLbeta type. A PfEMP1 cloned from a distinct ICAM-1 binding variant, the A4 parasite, contains a DBLbeta domain and a C2 domain in tandem arrangement similar to the A4tres PfEMP1. Anti-PfEMP1 antisera implicate the DBLbeta domain from A4var PfEMP1 in ICAM-1 adhesion. The identification of a P. falciparum ICAM-1 binding domain may clarify mechanisms responsible for the pathogenesis of cerebral malaria and lead to interventions or vaccines that reduce malarial disease.     

Plasmodium falciparum erythrocyte membrane protein 1 functions as a ligand for P-selectin.

The malarial protein Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is a parasite protein that is exported to the surface of the infected erythrocyte, where it is inserted into the red cell cytoskeleton in the second half of the parasite life cycle. The surface expression of PfEMP1 coincides with the occurrence of the adhesion of infected erythrocytes to vascular endothelium. This protein has been shown to interact with CD36, intercellular adhesion molecule-1 (ICAM-1) and chondroitin sulfate A (CSA). In this study, it is demonstrated by affinity purification and western blot analysis that PfEMP1 also functions as a cell surface ligand for P-selectin, an adhesion molecule that has been shown to mediate the rolling of infected erythrocytes under physiologic flow conditions, leading to a significant increase in adhesion to CD36 on activated platelets and microvascular endothelium.     

Plasmodium falciparum erythrocyte membrane protein 1 is a parasitized erythrocyte receptor for adherence to CD36, thrombospondin, and intercellular adhesion molecule 1.

Adherence of mature Plasmodium falciparum parasitized erythrocytes (PRBCs) to microvascular endothelium contributes directly to acute malaria pathology. We affinity purified molecules from detergent extracts of surface-radioiodinated PRBCs using several endothelial cell receptors known to support PRBC adherence, including CD36, thrombospondin (TSP), and intercellular adhesion molecule 1 (ICAM-1). All three host receptors affinity purified P. falciparum erythrocyte membrane protein 1 (PfEMP1), a very large malarial protein expressed on the surface of adherent PRBCs. Binding of PfEMP1 to particular host cell receptors correlated with the binding phenotype of the PRBCs from which PfEMP1 was extracted. Preadsorption of PRBC extracts with anti-PfEMP1 antibodies, CD36, or TSP markedly reduced PfEMP1 binding to CD36 or TSP. Mild trypsinization of intact PRBCs of P. falciparum strains shown to express antigenically different PfEMP1 released different (125)I-labeled tryptic fragments of PfEMP1 that bound specifically to CD36 and TSP. In clone C5 and strain MC, these activities resided on different tryptic fragments, but a single tryptic fragment from clone ItG-ICAM bound to both CD36 and TSP. Hence, the CD36- and TSP-binding domains are distinct entities located on a single PfEMP1 molecule. PfEMP1, the malarial variant antigen on infected erythrocytes, is therefore a receptor for CD36, TSP, and ICAM-1. A therapeutic approach to block or reverse adherence of PRBCs to host cell receptors can now be pursued with the identification of PfEMP1 as a malarial receptor for PRBC adherence to host proteins.     

Identification of a conserved Plasmodium falciparum var gene implicated in malaria in pregnancy

The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family is a highly polymorphic class of variant surface antigens encoded by var genes that play an important role in malaria pathogenesis. This report describes the unexpected finding that 1 of the var genes encoding a PfEMP1 variant that binds to the host receptor chondroitin sulfate A (CSA) and is implicated in malaria in pregnancy is well conserved among P. falciparum isolates worldwide. The N-terminal domains of this PfEMP1 variant are especially highly conserved, whereas the functional CSA binding domain is more variable. Analysis of var gene expression in placental parasites from primigravid women in Malawi did not support a role for this conserved gene in placental infection but identified a second commonly occurring var gene. These results indicate the need for reevaluation of previous assumptions of a minimal overlap between var gene repertoires from different parasite isolates.     

Assignment of functional roles to parasite proteins in malaria-infected red blood cells by competitive flow-based adhesion assay

Adhesion of parasitized red blood cells (PRBCs) to endothelial cells and subsequent accumulation in the microvasculature are pivotal events in the pathogenesis of falciparum malaria. During intraerythrocytic development, numerous proteins exported from the parasite associate with the RBC membrane skeleton but the precise function of many of these proteins remain unknown. Their cellular location, however, suggests that some may play a role in adhesion. The adhesive properties of PRBCs are best studied under flow conditions in vitro; however, experimental variation in levels of cytoadherence in currently available assays make subtle alterations in adhesion difficult to quantify. Here, we describe a flow-based assay that can quantify small differences in adhesion and document the extent to which a number of parasite proteins influence adhesion using parasite lines that no longer express specific proteins. Loss of parasite proteins ring-infected erythrocyte surface antigen (RESA), knob-associated histidine-rich protein (KAHRP) or Plasmodium falciparum erythrocyte membrane protein 3 (PfEMP3) had a significant effect on the ability of PRBCs to adhere, whereas loss of mature parasite-infected erythrocyte surface antigen (MESA) had no effect. Our studies indicate that a number of membrane skeleton-associated parasite proteins, although not exposed on the RBC surface, can collectively affect the adhesive properties of PRBCs and further our understanding of pathophysiologically relevant structure/function relationships in malaria-infected RBCs.     

Antibodies to a histidine-rich protein (PfHRP1) disrupt spontaneously formed Plasmodium falciparum erythrocyte rosettes.

Cerebral involvement in Plasmodium falciparum malaria is associated with sequestration of infected red blood cells and occlusion of cerebral vessels. Adhesion of infected erythrocytes along the vascular endothelium as well as binding of uninfected erythrocytes to cells infected with late-stage asexual parasites (rosetting) may be important in erythrocyte sequestration. We report that the recently discovered rosetting phenomenon shares characteristics with other human cell-cell interactions (heparin sensitivity, temperature independence, Ca2+/Mg2+ and pH dependence). Mono- and polyclonal antibodies specific for PfHRP1, a histidine-rich protein present in the membrane of P. falciparum-infected erythrocytes, disrupt rosettes but do not affect attachment of infected erythrocytes to endothelial cells. The inhibitory anti-PfHRP1 antibodies reacted with rosetting parasites in indirect immunofluorescence and with P. falciparum polypeptides of Mr 28,000 and Mr 90,000 in immunoprecipitation and immunoblotting, respectively. No inhibitory effects on erythrocyte rosetting were obtained with antibodies to related histidine-rich or other antigens of P. lophurae or P. falciparum. Whether the epitope that mediates rosetting, and is recognized by the anti-PfHRP1 antibodies, is located on PfHRP1 or on a crossreactive antigen remains to be established. The results suggest that endothelial cytoadherence and erythrocyte rosetting involve different molecular mechanisms.     

The duffy-binding-like domain 1 of Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is a heparan sulfate ligand that requires 12 mers for binding

The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), present on the surfaces of parasitized red blood cells (pRBC), mediates rosetting, a virulent phenotype. Here, we show that pRBC specifically bind heparan sulfate (HS) and heparin onto their surfaces and that the rosetting ligand PfEMP1 specifically adheres to heparin-Sepharose when extracted from the surfaces of radioiodinated infected RBC. An analysis of the binding properties of the different regions of PfEMP1 provides evidence that the Duffy-binding-like domain-1 (DBL-1) is the predominant ligand involved in HS and heparin binding. Soluble DBL-1 requires a minimal heparin fragment size of a 12-mer ( approximately 4 kd) for binding and is critically dependent on N-sulfation. A 12-mer is also the minimal heparin fragment that disrupts naturally formed rosettes. DBL-1 binds specifically to erythrocytes and also to HS from endothelial cells and human aorta but not to chondroitin sulfate A, suggesting that different PfEMP1s mediate adhesion to distinct glycosaminoglycans in individual malaria parasites. Present data suggest that HS on endothelial cells may also be involved in the sequestration of pRBC. Elucidation of these binding mechanisms opens up new possibilities for therapeutic strategies targeting adhesive interactions of pRBC.