疟原虫入侵红细胞机制研究进展

在分类上 ,Ｌｅｖｉｎｅ等根据疟原虫的裂殖子和子孢子具有顶端复合物的超微结构 ,将疟原虫与等孢球虫 ,肉孢子虫 ,弓形虫等统归入顶端复合物门〔1〕。他们拥有特征性的顶端细胞器 ,包括顶突及极环 ,顶凹 ,棒状体 ,微线体 ,球形体等。这种细胞器常用于侵袭或迁移入宿主细胞。原     

间日疟原虫入侵网织红细胞相关蛋白的研究进展

间日疟原虫是世界上分布最广泛的疟原虫,也是造成非洲以外地区人群感染疟疾的主要原因。间日疟原虫优先入侵网织红细胞,呈现高度的种特异性。间日疟原虫网织红细胞结合蛋白（PvRBP）家族作为入侵配体,介导了间日疟原虫入侵网织红细胞的新途径,是重要的免疫靶点。其中PvRBP2b与转铁蛋白受体1(TfR1), PvRBP2a与CD98的相互作用对间日疟原虫入侵网织红细胞至关重要。Pvrbp家族具有高度多态性并且可产生免疫逃避,能够增加间日疟入侵的效率和致病的严重程度。随着对间日疟原虫入侵分子机制研究的日益加深,研究产生高滴度抗体的疟疾疫苗将成为有效预防和控制疟疾的关键方法。本文就网织红细胞在间日疟原虫感染中的作用,以及Pv RBP家族在人群产生免疫应答的研究进展作一综述。     

经化学和酶处理的红细胞膜对恶性疟原虫裂殖子入侵...

By treating chemically and enzymatically erythrocytic membrane to change its structure and properties, the recognition of merozoite to erythrocyte and the effect of erythrocyte skeleton protein on the invasion of P. falciparum (Fc c-1/HN) were studied. It was found that the invasion of merozoite into erythrocyte digested with trypsin was greatly decreased; merozoite invasion into the erythrocyte treated with neuraminidase or wheat germ agglutinin (WGA) was partially inhibited; erythrocytes treated with cross-linker diamide and depolymerizer colchicine, N-ethyl maleinimide (NEM) of skeleton protein had evident resistance to invasion; the invasion of merozoite into erythrocyte treated with 2.0 mM of NEM was completely blocked.     

恶性疟原虫疫苗研究：IX.主要裂殖子表面蛋白1C端类表皮…

恶性疟原虫主要裂殖子表面蛋白１（ＭＳＰ１）在其分子Ｃ－端ＭＰＳ－１１９具有两个类ＥＧＦ结构，其中类ＥＧＦ－１为特异性抗体抑制原虫侵入细胞的靶位之一。本文通过酚－氯仿抽提，乙醇沉淀法提取恶性疟原虫（ＦＣＣ－１ＨＮ株）基因组ＤＮＡ，再用ＰＣＲ扩增类ＥＧＦ－１基因，经酶切纯化后插入质粒ｐＧＥＭ３Ｚｆ（＋）中，转化大肠杆菌ＤＨ５ａ，经ＰＣＲ筛选及双酶切鉴定，筛选出含类ＥＧＦ－１基因的阳性克隆子。     

疟原虫裂殖子主要表面蛋白1（MSP1）的研究进展

本文简述了疟原虫殂了主要表面蛋白１（ＭＳＰ１）的分子结构、功能以及在人群中诱导的免疫应答。对恶怀疟原虫ＭＳＰ１疫苗的动物和人体试验结果进行了分析，对ＭＳＰ１知诊断抗原分子和疟疾疫苗候选抗原的应用前景进行了探讨。     

恶性疟原虫裂殖子表面蛋白疟疾疫苗的研究进展

疟疾是一种危害严重的虫媒传染病，在疟原虫对抗疟药物的耐药性及媒介蚊对杀虫剂耐药性日益增强的今天，寻求一种新型，高效，安全的抗疟途径－抗疟疾疫苗的研制备受科研人员的关注。本对恶性疟原虫裂殖子表面蛋白抗疟疾疫苗的研究进展作一概述。     

重症疟疾相关分子机制的研究进展

由恶性疟原虫感染引起的疟疾导致全球每年100余万病例死亡,其中以脑型疟为代表的重症疟疾是引起疟疾患者死亡的主要原因。目前在临床上对重症疟疾的诊断、病理学分析以及治疗策略方面已比较成熟,但是对重症疟疾发生和发展过程中涉及的分子机制尚未完全清楚。该文对重症疟疾相关的关键分子及其调控机制的研究进展作一综述。     

约氏疟原虫重组裂殖子表面蛋白免疫原性的研究

目的 检测约氏疟原虫裂殖子表面蛋白C端相对分子质量为41 000重组蛋白的抗原性和免疫原性,对其抗虫感染效果进行评价,为疟疾DNA疫苗的研究提供基础资料.方法 采用重组表达质粒pPGEX-2T-PyMSP1在大肠杆菌中表达的融合蛋白,免疫BALB/c小鼠,2周后用约氏疟原虫子孢子感染小鼠.用酶联免疫吸附试验(ELISA)测定抗MSP1抗体滴度,MSP1融合蛋白特异性免疫反应测定,MSP1对小鼠免疫保护作用.结果 免疫11 d后抗体水平开始上升,到42 d达到最高峰,各时段抗体滴度分别为:第11天1:2 183、第21天1:38 115、第42、63、86和第124天均维持在1:798 560水平;ELISA检测免疫后第21天小鼠抗MSP1的IgG、IgM、IgG1、IgG2a、IgG2b和IgG3,其405 nm波长的吸光度(A405)依次为1.82±0.61、0.33±0.05、2.35 ±0.77、1.14±0.40、2.22±0.58、0.18±0.02.免疫后的小鼠体内产生特异性保护免疫,子孢子攻击感染20 d后,原虫密度有较快的下降.结论 所表达的重组约氏疟原虫裂殖子表面蛋白,具有一定的抗原性和免疫原性,能够诱导小鼠产生特异性保护抗体,并且该抗体能够维持在较高的水平.     

间日疟原虫不同MSP-1等位基因型形态学观察

目的　比较两种不同等位基因型间日疟原虫生物学形态特征。方法　现场采集间日疟病人血样并进行基因分型 ,镜下观察形态并测量大小。结果与结论　 72份现场分离株基因分型为Sal- 1型 4 0份 ,Belem型 2 5份 ,混合感染 7份 ,均查到典型的间日疟原虫 ,6例多重感染病例均发现在海南分离株 ,多重感染与基因型混合感染无关联。测量正常红细胞、寄生红细胞、环状体以及核大小差别有显著意义 ,Belem型比Sal- 1型大 ,两种不同基因型差异的分子机制需进一步探讨     

Toll样受体与疟原虫侵染关系的研究进展

为深入了解疟原虫在侵染、繁殖过程中的分子机制,本综述从Toll样受体(Toll like receptor,TLR)与疟原虫的相互作用关系入手,探讨疟原虫在突破机体防御屏障后如何被TLR识别,并启动下游炎症反应的机制。其中涉及到的部分重要结构保守的生物大分子有成为新型药物靶分子的潜在特性。     

大肠埃希菌表达的恶性疟原虫裂殖子表面蛋白MSP1-42的免疫原性

目的纯化大肠埃希菌Rosettagami（DE3）表达的可溶性裂殖子表面蛋白1C末端蛋白（MSP1-42,3D7株）,检测其体外抑制恶性疟原虫生长的效果。方法利用大肠埃希菌Rosettagami（DE3）为宿主菌诱导表达MSP1-42,用带组氨酸标签的镍柱纯化可溶性的MSP1-42。6只新西兰白兔随机分为免疫组和对照组,每组3只。用MSP142与弗氏佐剂乳化后,皮下注射,抗原免疫剂量每次为200“g／只,共免疫4次,每次间隔2周。佐剂对照组以PBS代替抗原同法免疫。免疫前及末次免疫2周后取血,用酶联免疫吸附试验和间接荧光抗体试验检测血清中特异性抗体及其与天然抗原的反应,用含10％和20％免疫血清的培养基体外培养恶性疟原虫（海南分离株,Fcc1／HN）,检测免疫血清体外抑制恶性疟原虫生长的效果。结果经镍柱纯化后获得纯度为95％以上的MSP1-42蛋白;免疫组个体在第4次免疫后血清特异性抗体的滴度依次为1：640000、1：640000、1：160000,间接荧光抗体试验检测表明MSP1-42免疫兔血清与恶性疟原虫表面蛋白有阳性反应;免疫血清能抑制恶性疟原虫在体外生长,在10％浓度时,3只免疫兔血清的抑制率依次为（51．94-24．2）％、（29．4±8．6）％和（86．7±7．4）％,在20％浓度时,抑制率分别为（93．3±7．5）％、（65．3±10．6）％和（96．4±1．0）％。结论大肠埃希菌Rosettagami（DE3）表达的MSP142蛋白免疫血清能识别恶性疟原虫天然抗原,体外培养能抑制恶性疟原虫的生长。     

转基因技术在疟原虫药物抗性机制研究中的应用

疟疾是世界上危害人类健康最严重的感染性疾病之一.随着抗疟药物的广泛使用,疟原虫抗药性问题日趋严重.开展疟原虫药物抗性机制的研究,有助于开发新的药物以及制定用药策略.采用疟原虫转基因的方法能够从分子水平证实抗性基因与药物敏感的相关性以及基因突变在药物抗性产生中所起的作用.该文综述了疟原虫转基因技术在氯喹和磺胺多辛-乙胺嘧啶药物抗性机制研究中的应用.     

Antibodies to a merozoite surface protein promote multiple invasion of red blood cells by malaria parasites

The 40-50 kDa merozoite surface antigen (MSA2) is a candidate molecule for use in a malaria vaccine. The gene for MSA2 from the 3D7 isolate of Plasmodium falciparum was amplified by polymerase chain reaction and cloned into the bacterial expression vector pGEX-3X to obtain a fusion protein of MSA2 with Schistosoma japonicum glutathione S-transferase. The recombinant fusion protein was used to immunize rabbits. After four injections, the sera had Western blotting and immunofluorescence titres of 10(-6). Immune sera, and immunoglobulin (Ig)G, F(ab)'2, F(ab) prepared from the immune sera, were assessed for their effects on the growth of 3D7 parasites in vitro by microscopy and a [3H]-hypoxanthine incorporation assay. The antibodies did not significantly inhibit red blood cell invasion and parasite growth when added to cultures as 10% v/v serum or as immunoglobulin preparations at concentrations up to 200 microg ml(-1). However, in the presence of IgG or F(ab)'2, but not F(ab), antibodies to MSA2, the proportions of red blood cells invaded by more than one merozoite increased significantly. Multiple invasion is attributed to merozoites cross-linked by bivalent antibodies, attaching to and subsequently invading the same red cell. These observations have a bearing on the evasion of host immune responses by the parasite and the use of full-length recombinant MSA2 protein in a malaria vaccine.     

2011-2013全国输入性三日疟与卵形疟疫情分析

目的分析我国输入性三日疟与卵形疟发病趋势和病例分布特征,为消除疟疾提供依据。方法利用中国疾病预防控制中心疾病监测信息报告管理系统(网络直报系统),收集2011—2013年全国三日疟及卵形疟疫情数据资料,应用SAS 9.2和ArgGIS 10.0软件就病例增长趋势和分布特征进行分析。结果我国2011—2013年共报告三日疟病例97例,卵形疟病例174例,均为输人性病例。其中,三日疟病例各年分别报告17例、22例和58例,分布于我国的7个、8个和14个省份;卵形疟病例各报告15例、34例和125例,分布于2个、10个和18个省份。自非洲输入的三日疟和卵形疟为240例(88.56%),其中自西非与中非输入共219例(80.81%);自东南亚输入16例(5.90%)。结论我国输入性三日疟与卵形疟病例呈逐年上升趋势,各地应加强鉴别诊断和防治。     

Mechanisms of drug resistance in malaria

Plasmodium falciparum causes the most severe form of human malaria which directly results in over two million deaths per year. As there is not yet a useful vaccine against this disease the major form of treatment and control is the use of chemotherapeutic agents. Unfortunately the parasite has managed to devise mechanisms that allow it to evade the action of almost all the antimalarials in our arsenal. The antifolate drugs include the dihydrofolate inhibitors pyrimethamine and proguanil as well as the sulfones and sulfonamides. These antimalarials act on enzymes in the folate pathway. The mechanism of resistance to these compounds involve mutations in the target enzyme that decrease the affinity of binding of the drug. A second major group of antimalarials include the quinine-like compounds. Quinine was one of the first compounds used to treat malaria and the related drug chloroquine is the most important antimalarial. Mefloquine and halofantrine were developed in response to major problems with the spread of chloroquine resistance. Chloroquine resistance is due to the ability of the parasite to decrease the accumulation of the drug in the cell. The exact mechanism that allows this is still under investigation although at least one protein has been identified that affects the accumulation of this important antimalarial.     

Genetic diversity in the C-terminal 42 kDa region of merozoite surface protein-1 of Plasmodium vivax (PvMSP-1(42)) among Indian isolates

Plasmodium vivax merozoite surface protein 1 (PvMSP-1) is a leading malaria vaccine candidate. This protein is processed to give rise to various sized fragments during merozoite maturation. Here, we describe the analysis of genetic diversity in the 42 kDa C-terminal part of this protein among 33 Indian P. vivax isolates. A total of 27 haplotypes with 72 mutations and 0.0212 ± 0.0005S.D. over all π nucleotide diversity were observed among the isolates. Twenty-six of 27 haplotypes reported here were new as they have not been reported so far from any other country. The difference between non-synonymous (dN) and synonymous (dS) mutations was found to be positive (0.0081 ± 0.0051) for the entire 42 kDa region. Further analysis revealed that 33 kDa (MSP-1₃₃) fragment of the MSP-1₄₂ was highly polymorphic with π nucleotide diversity 0.0290 ± 0.0007S.D. The dN-dS for this region of MSP-1 was also positive (0.0114 ± 0.0071S.E.). On the other hand, there was no non-synonymous mutation in the 19 kDa (MSP-1₁₉) fragment of the MSP-1₄₂ and thus it was highly conserved. In conclusion, MSP-1₃₃ fragment was highly polymorphic and appeared to be under diversifying selection whereas there was no selection at MSP-1₁₉ region among the isolates. Present study will be helpful for the development of PvMSP-1 based vaccine against P. vivax malaria.     

Spatial and temporal variations of malaria epidemic risk in Ethiopia: factors involved and implications

The aim of this study was to describe spatial and temporal variations in malaria epidemic risk in Ethiopia and to examine factors involved in relation to their implications for early warning and interpretation of geographical risk models. Forty-eight epidemic episodes were identified in various areas between September 1986 and August 1993 and factors that might have led to the events investigated using health facility records and weather data. The study showed that epidemics in specific years were associated with specific geographical areas. A major epidemic in 1988 affected the highlands whereas epidemics in 1991 and 1992 affected highland-fringe areas on the escarpments of the Rift Valley and in southern and north-western parts of the country. Malaria epidemics were significantly more often preceded by a month of abnormally high minimum temperature in the preceding 3 months than based on random chance, whereas frequency of abnormally low minimum temperature prior to epidemics was significantly lower than expected. Abnormal increases of maximum temperature and rainfall had no positive association with the epidemics. A period of low incidence during previous transmission seasons might have aggravated the events, possibly due to low level of immunity in affected populations. Epidemic risk is a dynamic phenomenon with changing geographic pattern based on temporal variations in determinant factors including weather and other eco-epidemiological characteristics of areas at risk. Epidemic early warning systems should take account of non-uniform effects of these factors by space and time and thus temporal dimensions need to be considered in spatial models of epidemic risks.     

辽宁丹东间日疟原虫裂殖子表面蛋白1等位基因型分析

用套式PCR方法扩增辽宁丹东地区间日疟原虫裂殖子表面蛋白1(MSP-1)基因ICB5-ICB6片段,经PvuⅡ酶切和琼脂糖凝胶电泳,对产物进行序列分析。结果显示,11份镜检确诊的间日疟患者血液标本经套式PCR扩增均出现大小约为470 bp(Sal-1型)或400 bp(Belem型)的特异性片段。经PvuⅡ内切酶消化后,其中5份血样(470 bp),出现120和350 bp酶切片段,为Sal-1型;其余6份血样(400 bp)中,1份出现400 bp片段,为Belem型,1份出现120和280 bp两种酶切片段,为重组Ⅲ型,4份出现120和240 bp两种酶切片段,为朝鲜型。辽宁省丹东地区的间日疟原虫PvMSP-1基因存在3种不同的等位基因型,以Sal-1型和朝鲜型为主,但无不同等位基因型的混合感染。