疫苗候选抗原Pvs48/45在中缅边境的遗传多样性特点

目的 了解间日疟原虫传播阻断疫苗候选抗原Pvs48/45在中缅边境地区的基因多态性和自然选择特点。方法 提取39例来自中缅边境主要流行区(Laiza)的间日疟原虫基因组DNA,采用巢式PCR(nest-PCR)扩增Pvs48/45基因开放阅读区(Open reading frame, ORF);通过MEGA 4.0、DnaSP v5.10和NETWORK 4.6对Pvs48/45基因多态性和自然选择特点进行分析。结果 研究发现了6个突变位点,均为非同义突变(E35K ,H211N ,K250N ,D335Y,A376T,K418R),导致了5种单倍型;Pvs48/45基因的核苷酸多态性水平极低(π=0.00064),CRDⅢ区最高(π=0.00163);多种中性检验均表明Pvs48/45基因处于平衡选择;种群进化分析和单倍型网络图显示Pvs48/45具有较强的地理分化,且H2型为中缅边境地区频率最高的单倍型。结论 Pvs48/45在中缅边境地区遗传多样性很低,且在进化过程中经历平衡选择,提示其可作为传播阻断疫苗候选靶点;Pvs48/45在全球具有较强的地理分化,应根据地区遗传特点开发更加有效的传播阻断疫苗。     

间日疟原虫特异性DNA片段的克隆和鉴定

本文从间日疟患者血液中分离出间日疟原虫,将其基因组 DNA 片段克隆到载体 pUC12质粒中,构建了间日疟原虫 DNA 文库。利用质粒的遗传标志初步筛选重组克隆;用~(32)P 标记的间日疟原虫DNA,人白细胞 DNA 和恶性疟原虫 DNA 为探针分别作菌落杂交,差异筛选出4株间日疟原虫特异的重组克隆,命名为 pVA1—4。然后酶切鉴定其插入片段,并用 Southern blot 分析,表明重组质粒 pVAl 含有间日疟原虫特异性 DNA 片段。     

对间日疟病程初期原虫密度的观察

滇南的实验结果显示，人工接种当地间日疟原虫子孢子后，经短潜伏期发病的３８名志愿者，首次见虫时间为８－１３ｄ，首次见虫和临床初发时的原虫密度分别为０．２－１．６和０．６－４０４０个／μｌ。造成如此明显差异的原因，似与虫现期和临床初发间的时间距离密切有关，表现为感染后临床初发的时间越早，多数病例于首次见虫时的原虫密度越低，反之则高。文中讨论了这一问题在病原生物学和流行病学上的重要性。     

Evaluation of chloroquine as a potent anti-malarial drug: issues of public health policy and healthcare delivery in post-war Liberia

Chloroquine-resistant plasmodium falciparum malaria is a serious public health threat that is spreading rapidly across Sub-Saharan Africa. It affects over three quarters (80%) of malarial endemic countries. Of the estimated 300-500 million cases of malaria reported annually, the vast majority of malarial-related morbidities occur among young children in Africa, especially those concentrated in the remote rural areas with inadequate access to appropriate health care services. In Liberia, in vivo studies conducted between 1993 and 2000 observed varying degrees of plasmodium falciparum malaria infections that were resistant to chloroquine, including sulfadiazine-pyrimethamine. As the country emerges from a prolonged civil war, the health care delivery system may not be adequately prepared to implement an effective nation-wide malarial control strategy. As a result, the management of uncomplicated malaria in Liberia poses a significant public health challenge for the government-financed health care delivery system. Therefore, based on extensive literature review, we report the failure of chloroquine as an effective first-line drug for the treatment of uncomplicated plasmodium falciparum malaria in Liberia and recommend that national health efforts be directed at identifying alternative drug(s) to replace it.     

Anti-gamete antibodies block transmission of human vivax malaria to mosquitoes

Antibodies were raised in rabbits by immunizing against fresh unfixed or cryopreserved female gametes of the human malaria pathogen Plasmodium vivax. The antibodies were shown to react with the surface of gametes by the indirect immunofluorescent test. When parasite isolates from P. vivax infected individuals were fed through a membrane to Anopheles tessellatus mosquitoes in the presence of immune rabbit sera, they completely blocked the infectivity of the parasite isolates to the vector. Immunoglobulins separated from these sera also blocked infectivity to the same extent as did the immune sera indicating that antibodies were responsible for the transmission blocking effect of the sera. This study indicated that P. vivax like other malaria parasites is highly susceptible to anti gamete transmission blocking immunity.     

抑制夏氏疟原虫无性体及蚊媒传播的单克隆抗体

以夏氏疟原虫(Plasmodium chabaudi chabaudi)AS株配子体免疫小鼠后,制备了两种单克隆抗体,McAb5E(5E)及McAb5F(5F);5E既有阻断疟疾传播的活性又有对抗红细胞内期无性体的保护作用。通过间接免疫荧光试验,5E可与各无性阶段、配子体及小配子起反应,而5F则仅与环状体、配子体及小配子起作用。这种抗无性体及阻断传播的活性是由于无性体与配子体有共同的表位,还是由于交叉反应所致,尚待进一步研究。     

Antigenic variation and cytoadherence of PfEMP1 of Plasmodium falciparum-infected erythrocyte from malaria patients

Objective To approve a theoretical basis for the molecular pathogenesis of human cerebral malaria and treatment with prevention.Methods The blood samples were collected from 24 patients with cerebral malaria, 143 wit h falciparum malaria, 34 with vivax malaria and 20 healthy controls from the end emic areas of Yunnan Province, China. Using the sodium dodecyl sulfate-polya crylamide gel electrophoresis (SDS-PAGE) technique, we determined the molecular mass (Mr) of these Plasmodium falciparum (P. falciparum) erythrocyte membr ane protein 1 (PfEMP1) molecules. Results Our findings indicate that higher molecular mass (260 kDa-320 kDa) forms of Pf E MP1 were expressed on parasitized erythrocyte (PE) from human cerebral malaria p a tients. Compared with PfEMP1 expressed on PE from human cerebral malaria patien ts, the expression of PfEMP1 and Plasmodium vivax (P. vivax) erythrocyte me mbrane protein 1 (PvEMP1) on PE from falciparum malaria patients and vivax malar ia patients did not have multiple bands of PfEMP1 of ≥260 kDa, but had a PfEMP 1 with molecular mass of 240 kDa and a PvEMP1 with molecular mass of 180 kDa b and separately. Healthy controls expressed an EMP of molecular mass of 140 k Da.Conclusion Results confirm the antigenic variation of higher molecular mass of PfEMP1 whos e molecular mass is equal to or exceeds 260 kDa-320 kDa on PE of patients with cerebral malaria. Our results show that the binding of large antigenic variabi lity PfEMP1 molecular mass of 260 kDa-320 kDa on PE from human cerebral malari a patients with diverse receptor molecules on the endothelial cell (EC) of the c erebral microvessels may be involved in the molecular pathogenesis of cerebral m alaria.     

伯氏疟原虫在-20℃保存下原虫复苏成功率

将伯氏疟原虫感染小鼠,当其血原虫密度大于３０－００ ％ ,置病鼠于－ ２０ ℃低温冰箱保存。经不同时间后,迅速解冻,心脏取血,经腹腔内接种健康小鼠,以观察原虫复苏成功率。结果表明：低温保存５０ ～１００ ｄ 和１０１～１５５ ｄ,病鼠复苏成功率分别为３３－３３ ％ 和２０－００ ％ 。提示该法仍不适为一种简便可行,行之有效的低温保存方法。     

间日疟控制和消除的挑战及其对策研究进展

间日疟地理分布广,是现今疟疾控制和消除的最大挑战之一。本文通过查阅各类相关数据库,综述了间日疟控制和消除的挑战及其应对策略研究进展。各类来源的研究资料显示间日疟更易于传播,媒介控制措施效果差;无症状和亚显微镜检测密度带虫者比例高,常规检测困难;磷酸伯氨喹啉(唯一根治药)安全性低。为应对这些挑战,现正在从传播阻断、实验诊断、抗疟药物和方案等方面开展研究。     

西盟县1991～2009年疟疾疫情监测结果分析

目的分析1991～2009年西盟县疟疾发病及流行情况,评价发热病人疟疾血检措施的落实情况。方法将历年收集的疟疾疫情资料,现症病人、发热病人血检监测结果、居民带虫结果及相关流行病学资料进行回顾性统计分析。结果1991～2009年共报告疟疾疫情病例7 760例,其中间日疟7 271例,占93.70%,1991年发病率为39.02%;2009年发病率为1.80%;2009年与1991年发病率比较,下降95.39%。发热病人疟疾血检阳性8 216例,阳性率5.43%,其中间日疟7 670例,占93.35%;西盟县以间日疟流行为主。阳性病例中当地居民当地感染占88.49%;以当地感染为主。疟疾病例数,居民带虫率、疟疾病灶点数均以1998、1999年为最高;当地居民外出人员的疟疾感染率为6.02%,外来人口血检阳性率为20.81%,其中外地和境外感染输入阳性率为24.76%。病灶点2009年与1991年相比下降93.33%。结论近年来西盟县的疟疾发病率呈大幅下降,疟疾流行严重的态势得到了有效控制,但鉴于西盟县存在适宜传疟媒介繁殖的自然条件和以内源性疟疾感染为主的实际情况,疟疾疫情长期存在和出现反复的可能性不容忽视