约氏疟原虫感染对小鼠黑色素瘤的抑制作用

目的观察约氏疟原虫17XL虫株感染对小鼠黑色素瘤的抑制作用。方法取C57BL/6小鼠20只,腋下注射传代培养的B16F10黑色素瘤细胞;次日,将小鼠随机分为约氏疟原虫(P.y)感染组和对照组2组,10只/组;P.y感染组小鼠每只腹腔注射1×106个含虫红细胞率为20%的小鼠红细胞;对照组小鼠腹腔注射等量的C57BL/6小鼠正常红细胞。观察两组小鼠黑色素瘤出瘤时间并测量肿瘤的体积。结果 P.y感染组小鼠黑色素瘤出瘤时间为注射黑色素瘤细胞后(11.30±0.21)d,晚于对照组[(10.40±0.22)d](P0.05);自可精确测量瘤体起至实验终点,2组小鼠肿瘤均不断增长,P.y感染组瘤体体积均显著小于对照组(P均0.05);P.y感染组瘤体生长速度为(71.10±6.29)mm3/d,明显慢于对照组[(302.80±49.94)mm3/d](P0.05),且P.y感染组肿瘤每日生长速度亦明显慢于对照组(P均0.05)。结论约氏疟原虫感染可以延缓肿瘤出瘤时间,且对小鼠黑色素瘤瘤体的增长具有明显的抑制作用。     

Auxotrophs of Plasmodium falciparum dependent on p-aminobenzoic acid for growth.

The isolation of auxotrophic strains of a parasite offers new opportunities for studying parasitology. We have isolated cloned lines of Plasmodium falciparum that, unlike the parent line from which they were derived, rely on exogenous p-aminobenzoic acid (PABA) for growth. Isolation involved random mutagenesis of a cloned line of P. falciparum and subsequent selection of PABA-dependent parasites. Both parent and PABA-dependent clones were analyzed for PABA uptake and synthesis. Each clone takes up comparable amounts of PABA from the medium. The parent line, clone 3D7, can synthesize PABA de novo, whereas the PABA-dependent clones cannot. The requirement of exogenous PABA for growth by the auxotrophic strains coupled with their inability to synthesize PABA indicates that normal parasite growth can be completely supported by either synthesis or salvage. This work further clarifies the relationship between the availability of PABA and success of the parasite, an issue of debate from classic studies showing reduced parasite load in individuals on milk-fed diets.     

IL-10在约氏疟原虫感染过程中免疫调节作用的实验观察

目的探讨IL-10在疟原虫感染过程中的免疫调节效应。方法用约氏疟原虫感染DBA／2和BALB／c小鼠，取血，制薄血膜，染色后镜检疟原虫，计算红细胞感染率；用ELISA试剂盒检测小鼠血清IFN-γ和IL-10水平。结果DBA／2小鼠于感染后第21d自愈，血清IFN-γ在感染后第3d显著升高（6542pg／ml），之后逐渐下降，至感染后第12d仍高于未感染鼠；血清IL-10于感染后第6d显著升高（248pg／ml），并于感染后第15d达到峰值（980pg／ml）后下降。BALB／c小鼠感染后第6d红细胞感染率达57．5％，并于当日和次日全部死亡；血清IFN-γ仅于感染后第3d出现一过性升高，峰值为2225pg／ml而IL-10一直处于高水平状态，峰值为432pg／ml。结论小鼠感染约氏疟原虫后过早分泌的高水平IL-10对Th1反应具有明显的抑制效应，而IL-10适时的分泌可能与Th1向Th2反应的转换密切相关。     

抗约氏疟原虫感染过程中单核-巨噬细胞免疫效应的研究

目的　探讨单核 -巨噬细胞及其分泌的NO在抗疟原虫感染过程中的作用。方法　应用吉姆萨薄血膜染色法和腹腔注射鸡红细胞法分别检测红细胞感染率及单核细胞和腹腔MΦ的吞噬能力 ;通过Griess反应检测小鼠腹腔MΦ合成NO水平。结果　腹腔MΦ在感染后 6d吞噬率即达到高峰 ,单核细胞的数目和吞噬能力在感染 6d后开始增加 ,同时 ,虫体血症水平升高的趋势受到遏制 ;感染早期MΦ合成NO水平逐渐升高 ,但对虫体血症没有影响。结论　单核 -巨噬细胞数量的增加和巨大吞噬杀伤作用的发挥可削减并最终清除虫体血症 ;但感染早期MΦ合成NO水平逐渐升高的意义尚需进一步研究     

抗鼠疟免疫核糖核酸治疗约氏疟原虫感染的疗效观察

目的观察抗鼠疟免疫核糖核酸的疗效。方法以约氏疟原虫腹腔感染DBA／2和BALB／c小鼠，并用抗鼠疟免疫核糖核酸对其进行治疗。薄血膜染色，计数红细胞感染率；用ELISA试剂盒和Griess实验分别检测DBA／2小鼠牌细胞培养上清中IFN-γ和NO含量。结果注射正常核酸的BALB／c小鼠于感染后6～7d全部死亡，与其相比，注射免疫核糖核酸BALB／C小鼠虫体血症蜂值出现的时间被推迟2d，并且有20％的小鼠被治愈；注射免疫核糖核酸DBA／2小鼠牌细胞分泌的IFN-γ水平比对照组略有升高，但NO水平升高显著，其红内期原虫的清除时间也比对照组提前了4天。结论抗鼠疟免疫核糖核酸可使抵抗宿主的巨噬细胞活化状态得以进一步强化，其对约氏疟原虫感染所致的鼠疟具有一定疗效。     

抗斯氏按蚊中肠蛋白组分的抗体对约氏疟原虫卵囊的作用

目的 观察抗斯氏按蚊中肠蛋白组分的抗体对约氏疟原虫卵囊的抑制作用。 方法 解剖实验室饲养斯氏按蚊雌蚊，取中肠（胃）制备中肠蛋白抗原并免疫BALB/c小鼠（8只， 100 μg/只)， 共免疫4次， 每次间隔7～10 d，末次免疫后10 d，腋窝动脉取血，分离血清。用蛋白质印迹（Western blotting）分析中肠蛋白的免疫活性抗原。用葡聚糖凝胶过滤法获得相对分子质量（Mr）为38 000~50 000的蛋白。用该中肠蛋白免疫小鼠（12只， 100 μg/只)， 共免疫4次，每次间隔7~10 d。同时设PBS对照组。末次免疫后7 d，ELISA检测小鼠血清中的抗体，抗体效价≥1 : 2 560时，该免疫组小鼠和对照组小鼠经腹腔接种感染约氏疟原虫（约含2×10⁷个感染疟原虫的红细胞），感染后3 d取小鼠尾血镜检，雌配子体数＞2/10个视野的小鼠作为供血鼠，斯氏按蚊成蚊吸血后9 d解剖，计数中肠的卵囊数量。 结果 Western blotting显示斯氏按蚊中肠蛋白抗原的显色区带有8条，其中Mr 38 000~50 000的区带显色较清晰；实验组和对照组中肠卵囊感染率分别为28.70%（62/216）和51.09%（47/92）（P＜0.05），中肠卵囊指数分别为14.14（1 541/109）和26.02（1 223/47），两者差异有统计学意义（P＜0.01）。 结论 斯氏按蚊Mr 38 000~50 000中肠蛋白有免疫活性；针对该中肠蛋白的抗体对约氏疟原虫卵囊的发育有明显的抑制作用。     

大劣按蚊含硫脂蛋白基因在约氏疟原虫感染中的作用

目的分析大劣按蚊含硫脂蛋白(TEP1)基因在约氏疟原虫感染过程中的作用。方法根据GenBank中大劣按蚊TEP1基因序列设计带有T7启动子的引物,以大劣按蚊cDNA为模板,进行PCR扩增,纯化产物,体外转录试剂盒合成AdTEP1双链RNA。羽化1～2日的雌性大劣按蚊分3组(200只/组):TEP1干扰组、绿色荧光蛋白(EGFP)干扰组和对照组。TEP1、EGFP干扰组按蚊分别进行胸部微量注射AdTEP1双链RNA、EGFP双链RNA各147 ng,对照组未处理。干扰后3d,每组取15只按蚊,去头,以大劣按蚊核糖蛋白S7(AdS7)为内参进行半定量PCR,检测干扰效果。干扰后4d,用约氏疟原虫BY256荧光株感染3组大劣按蚊。感染后9d,每组各解剖25只蚊胃,记录感染率和感染度。结果对照组和EGFP干扰组AdTEP1的表达条带亮度基本一致,而TEP1干扰组AdTEP1的表达条带亮度非常微弱。感染后9 d,蚊胃卵囊数统计学分析表明,对照组、EGFP干扰组和TEP1干扰组感染率分别为(24±2.83)%、(24±0.71)%和(80±3.54)%;感染度分别为0.32±0.7、0.44±0.85和5.52±4.84...     

Possible involvement of platelets in Plasmodium yoelii nigeriensis malaria infection in mice

The possible involvement of platelets in the pathogenesis of malaria was examined by monitoring the changes in platelet function (bleeding time [BT] and thrombin time [TT]) concomitantly with changes in packed cell volume (PCV) and erythrocyte infection rate (EIR) in Plasmodium yoelii nigeriensis infection in mice. In untreated plasmodium-infected mice, there was a progressive reduction (day 1-7) in BT from 120.0 +/- 12.6 s to 77.5 +/- 5.9 s (p less than 0.005), a reduction in TT from 26.8 +/- 1.2 s to 17.8 +/- 1.2 s (p less than 0.005), an increase in EIR from 0 to 64.6 +/- 6.3% and a reduction in PCV from 44.9 +/- 1.9% to 21.5 +/- 3.9% (p less than 0.001). Mortality on day 9 was 100%. Antiplatelet serum treatment of plasmodium-infected mice protected against malaria and there was a blunting of the malaria-induced changes in platelet function, EIR and PCV. The values obtained in these rats were significantly higher than those of the untreated malarious mice. The respective values obtained on day 1 were comparable to those of control mice. Data obtained on day 7 were: BT, 106.4 +/- 7.4 s (p less than 0.05), TT, 22.7 +/- 1.1 s (p less than 0.05), EIR, 45.7 +/- 3.2% (p less than 0.01) and PCV, 39.5 +/- 2.0% (p less than 0.01). Mortality on day 9 of infection was 60%. The protection by antiserum was not due to its thrombocytopenic response as busulphan-induced thrombocytopenia did not have the same effect. These results suggest that platelets play an important role in malaria infection as well as in the attendant coagulopathic complications.     

体外观察一氧化氮对约氏疟原虫雄配子形成的影响

目的 体外观察一氧化氮（NO）对疟原虫雄配子形成的影响。 方法 约氏疟原虫感染DBA/2小鼠，制备薄血膜吉氏（Giemsa）染色观察小鼠原虫血症和配子体血症水平。并通过Griess反应检测脾细胞产生的NO水平。感染第4天，实验组小鼠注射不同剂量的一氧化氮发生剂（NOC5），对照组小鼠注射NOC5前体物质，分别采集其注射前、注射后30 min和60 min的尾静脉血；感染第6天，实验组小鼠注射一氧化氮合酶抑制剂（L-NMMA），对照组小鼠分别注射D-NMMA和PBS，分别采集其注射前、注射后4 h和8 h的尾静脉血。体外培养采集的血液，观察雄配子形成。 结果 感染后第4天和第6天，小鼠脾细胞合成NO水平分别为16.5 mmol/L和30.4 mmol/L，而雄配子形成数分别为11.33和0.66；感染第4 天小鼠注射1 mg NOC5 后30 min和60 min的雄配子形成数分别为5.33和2.66，显著低于其对照组（P＜0.01）；感染第6 天小鼠注射L-NMMA后8 h的雄配子形成数为1.83，显著高于其对照组（P＜0.01）。 结论 NO可直接抑制疟原虫雄配子形成，是导致疟疾自然传播阻断现象发生的主要效应分子。     

Glucose transport in cerebral microvessels during Plasmodium yoelii nigeriensis infection in mice

Plasmodium yoelii infected cerebral micro vessels of mice registered a significant increase in D-[U-14C] Glucose transport as compared to normal microvessels which was found to be time, temperature and concentration dependent. Metabolic inhibitors galactose, manose, 2-deoxy glucose and D-glucose showed noticeable inhibition of the same.     

Effect of ketotifen on the ultrastructure of the erythrocytic stages of Plasmodium yoelii

The effect on the morphology of Plasmodium yoelii of ketotifen treatment was different from that of chloroquine and other antimalarial drugs. Following administration of a low dosage of ketotifen, the parasite first developed a multilamellate pellicular complex which resembled a medullary sheath and then developed vacuoles and cavitations. The development of large multilamellate whorls consisting of a pellicular structure enclosing cytoplasm was the typical change which occurred.     

Supplement of L-Arg improves protective immunity during early-stage Plasmodium yoelii 17XL infection

L-arginine (L-Arg), the precursor of nitric oxide (NO), plays multiple important roles in nutrient metabolism and immune regulation. L-Arg supplement serves as a potential adjunctive therapy for severe malaria, because it improves NO bioavailability and reverses endothelial dysfunction in severe malaria patients. In this study, we investigated the effect of dietary L-Arg supplement on host immune responses during subsequent malaria infection using the Plasmodium yoelii 17XL - BALB/c mouse model. We have shown that pretreatment of mice with L-Arg significantly decreased parasitemia and prolonged the survival time of mice after infection. L-Arg supplement led to significant increases in activated CD4(+) T-bet(+) IFN-γ(+) T cells and F4/80(+) CD36(+) macrophages during early-stage infection, which were accompanied by enhanced synthesis of IFN-γ, TNF-α and NO by spleen cells. Moreover, L-Arg-pretreated mice developed more splenic myeloid and plasmacytoid dendritic cells with up-regulated expression of MHC II, CD86 and TLR9. In comparison, L-Arg treatment did not change the number of regulatory T cells and the level of anti-inflammatory cytokine IL-10. Taken together, our results showed that L-Arg pretreatment could improve the protective immune response in experimental malaria infection in mice, which underlines potential importance of L-Arg supplement in malaria-endemic human populations.     

Cerebral ammonia levels and enzyme changes during Plasmodium yoelii infection in mice.

Ammonia, lactate and glutamate levels and the activities of glutamine synthetase (GS), glutamate dehydrogenase (GDH), glutaminase (GLN), aspartate transaminase (AST), phosphofructokinase (PFK) and monoamine oxidase (MAO) were compared in the brain tissue of normal and P. yoelii infected mice. The brain lactate increased by 96% at peak parasitaemia. Cerebral ammonia also exhibited an increase in infected mice which was parasitaemia dependent, while glutamate remained almost unchanged. The brain glutamine synthetase registered an increase of 35% (P < 0.001) in post-mitochondrial fractions, this effect being perceptible even at low parasitaemia, but attained constancy at parasitaemia levels higher than 20%. The activity of monoamine oxidase and phosphofructokinase increased by 105% (P < 0.02) and 41% (P < 0.05) respectively while glutamate dehydrogenase decreased by 15% (P < 0.001). Glutaminase and aspartate transaminase were not significantly influenced by infection (tested only at high parasitaemia levels). It has been postulated that cerebral hypoxia and aberrations in ammonia metabolism may both contribute towards malaria induced cerebral complications.     

约氏疟原虫与伯氏疟原虫侵入期抗原的初步研究

目的　用针对鼠约氏疟原虫(Plasmodiumyoelii)侵入期的8种单克隆抗体,对约氏疟原虫和伯氏疟原虫(P.berghei)侵入期即动合子、裂殖子和子孢子棒状体和表面抗原检测分析。　方法　间接免疫荧光实验(IFA)对各侵入期抗原进行亚细胞结构定位,SDSPAGE及Western印迹对两种鼠疟原虫的不同侵入期进行抗原组分分析。　结果　经上述两种方法检测发现,顶端复合体抗原成分复杂,约氏疟原虫和伯氏疟原虫的棒状体有共同的抗原表位,约氏疟原虫的动合子与其自身的裂殖子有类似成分,也有各自独特的抗原。两种鼠疟原虫动合子抗原有类似成分。约氏疟原虫的子孢子具有与裂殖子、动合子不同的抗原成分。　结论　疟原虫侵入期棒状体和表面抗原在同一虫种的不同侵入期和不同虫种中有共同的抗原表位,也有各自的独特组分。     

Toll样受体在约氏疟原虫感染早期树突状细胞应答中的作用地位

目的探讨致死型约氏疟原虫(Plasmodium yoelii17XL,P.y17XL)感染早期,Toll样受体(Toll like receptor,TLR)在树突状细胞(dendritic cells,DCs)活化中的作用地位。方法用P.y17XL感染易感的BALB/c和抵抗的DBA/2小鼠,计数红细胞感染率;制备感染前和感染后第3d、5d小鼠脾细胞悬液,采用流式细胞分析技术检测两种小鼠感染不同时间脾细胞悬液中细胞内表达TLR9(Toll like receptor 9,TLR9)的DCs和细胞表面表达TLR4(Toll like receptor 4,TLR4)的DCs的百分含量。结果两种小鼠脾DCs细胞内TLR9的表达水平均于感染后第3d开始明显升高(P<0.01),在第5d达到最高水平(P<0.01),但两种小鼠相比无统计学意义。同时,两种小鼠DCs表面TLR4的表达水平均未见明显变化。结论在P.y17XL感染早期,TLR9可能是介导DCs活化的模式识别受体。     

Optimal concentration of p-aminobenzoic acid and folic acid in the in vitro assay of antifolates against Plasmodium falciparum

In vitro tests for Plasmodium falciparum sensitivity to pyrimethamine, sulfadoxine, and both drugs in combination were performed in four kinds of culture medium, each differing in p-amino benzoic acid (PABA) and folic acid concentrations. Results of the tests using pyrimethamine-sensitive and pyrimethamine-resistant isolates indicated that drug activity was reduced proportionally to the concentrations of these two growth factors in the medium. The optimal concentrations of PABA and folic acid for parasite growth and drug susceptibility, as evaluated by microscopic examination and by the extent of incorporation of radioactive 14C-pyrimethamine and 14C-sulfadoxine, were 10 ng/ml and 2 ng/ml, respectively. Depletion of PABA and folic acid from the medium had no effect on drug-resistant parasites but multiplication of drug-sensitive isolates was markedly reduced. Medium containing 0.5 ng/ml PABA and 10 ng/ml folic acid was the best for parasite growth regardless of the degree of drug sensitivity. Results obtained by using this medium agreed most closely with results from in vivo observations.     

Scanning electron microscopic observations of ookinete formation of Plasmodium yoelii yoelii in vitro

The ookinete formation and mature ookinete of Plasmodium yoelii yoelii were described. During the development from zygote to ookinete, at first a finger-shaped or a stick-shaped projection protruded from one side of zygote. The anterior end of the projection assumed a truncated cone shape. Following enlargement of the projection, the body of zygote gradually wrinkled and shrank and became smaller. An annular structure developed between the newly formed ookinete and the remaining body of zygote, which ultimately separated from the ookinete. The ookinete was banana-shaped. The surface of mature ookinetes was smooth. On the tip there was an apical complex showing truncated cone shape. Behind the apical end there were a few pellicular folds. Through the course of development of the ookinete the parasite constantly showed obvious movement. As the parasites protruding forward, longitudinal and spiral wrinkles appeared on their body surface.