Development of infective stage Leishmania promastigotes within phlebotomine sand flies

Midgut promastigotes were obtained from Phlebotomus papatasi and Lutzomyia longipalpis on days 3-7 after infection with cloned isolates of Leishmania major and Leishmania mexicana amazonensis, respectively, and examined as to their ability to initiate cutaneous infections in BALB/c mice. Sequential development of midgut promastigotes from a noninfective to an infective stage was confirmed for both the New World and Old World species. The generation of infective promastigotes from rapidly dividing avirulent populations occurred as early as day 3 and was well under way by day 4 after infective feed. Optimally infective promastigotes were recovered from midguts shortly after bloodmeal passage, coinciding with the time at which another bloodmeal is sought by the fly.     

Surface antigenic change during differentiation of a parasitic protozoan, Leishmania mexicana: Identification by monoclonal antibodies.

The fusion of SP2/0 myeloma cells with spleen cells from mice immunized with Leishmania mexicana amazonensis promastigotes produced hybridoma clones. Indirect immunofluorescent antibody assay with live leishmanias showed that the monoclonal antibody 6H12 recognized only the antigens bound to the surface of L. mexicana amazonensis promastigotes. It also showed that the antibody bound to neither amastigotes of this species nor to other Leishmania species--i.e., L. braziliensis braziliensis, L. tropica, and L. donovani. Monoclonal antibodies from three other clones (4D11, 4H9, and 6A11) were found to compete with 6H12 for binding to L. mexicana promastigotes. With lysates of [35S]methionine-labeled promastigotes, all four monoclonal antibodies precipitated the same triplet set of protein bands at the approximately equal to 68,000-dalton region, whereas another monoclonal antibody (6G5) precipitated a different band at approximately equal to 90,000 daltons. During differentiation of L. mexicana amazonensis from amastigotes to promastigotes, there was a 4- to 8-fold increase above the initial level in the binding of 6H12 monoclonal antibody to leishmanias, as detected by enzyme-linked immunosorbent assay and quantitative fluorometric assay, respectively. Thus, we have demonstrated the use of monoclonal antibodies as probes for antigens that change during leishmanial differentiation.     

Subcellular and taxonomic specificity of monoclonal antibodies to New World Leishmania

Murine monoclonal antibodies to flagellar, surface membrane and cytoplasmic antigens of New World Leishmania were assessed for their taxonomic specificity in enzyme-linked immunosorbent assays with three genera of the family Trypanosomatidae and three species and seven subspecies of the genus Leishmania. Antibodies exhibiting exclusive reactivity with either the flagellum, flagellar pocket, kinetoplast, or nucleus lacked specificity at all phylogenetic levels and, in fact, recognized epitopes common to cultured mammalian cells. Monoclonals to intracellular antigens were capable of distinguishing Leishmania from Trypanosoma and Endotrypanum. Antibodies reactive at the surface membrane could separate six isolates of L. braziliensis from three isolates of L. mexicana but the differences in antigen expression were frequently quantitative rather than qualitative. Antigenic variability within species and/or subspecies often exceeded that which was observed between species and/or subspecies. At least one monoclonal antibody was specific for a surface antigen peculiar to a subpopulation of promastigotes of an L. braziliensis panamensis isolate.     

应用单克隆抗体检测白蛉体内的前鞭毛体

以杜氏利什曼前鞭毛体为靶抗原的L12G9单克隆抗体(McAb),检测人工感染杜氏利什曼原虫的白蛉。当空腹雌蛉吸取病鼠血液后,分别饲养4、6、8和10d后解剖。吸血后4d,前鞭毛体较少。阳性率仅为15.9％;而10d,其感染程度较重,可获100％的阳性检出率。其阳性率与白蛉的感染程度呈正相关。另外又证明应用单克隆抗体检测时,原虫数不能低于11×10~7/ml,宜选择胃血完全消化后的白蛉,方可得到良好的效果。如捕获的白蛉,胃内前鞭毛体较少,则可经NNN基培养后,再进行检测,亦可获得同样效果。     

Application of Specific Monoclonal Antibodies for Characterization of Leishmania spp. Promastigotes Using Indirect Immunofluorescent and Immunoperoxidase Tests

Background: Different methods have been used for characterization of Leishmania promastigotes. Monoclonal antibodies are useful in characterization of   Leishmania spp . both amastogotes and promastigotes. Objective: Comparing the characterization of   Leishmania spp. promastigotes with immunoperoxidase test (Avidin-Biotin) techniques and an indirect immunofluorescent assay (IFA).   Methods: Application of specific monoclonal antibodies for characterization of different   Leishmania species. Immunoperoxidase tests (Avidin-Biotin) and indirect immunofluorescent assay (IFA) were employed for characterization of different   Leishmnia promastigotes from culture. Five monoclonal antibodies including LXXVIII-2E5- A8 (D2) specific for   L. donovani:L. infantum , IS2-2B4 (A11) specific for L. tropica, XCIV-H2- AB (T10) specific for   L. tropica, XLVI-5B8- B3 (T1) specific for L. major, and T7 reactive to both   L. major and L. tropica as well as an anti GP63 mAb were used. Results: The best result was obtained with the dilution of 1:50 for both mAb and conjugate. One hundred percent sensitivity and specificity was achieved for characterization of Leishmania promastogotes with both methods. Conclusion: As immunoperoxidase method needs less equipments compared to IFA technique, it would be a preferred method for characterization of promastigotes.     

Effect of macrophage infection by Leishmania on the proliferation of an antigen-specific T-cell line, TPB1, to a non-parasite antigen

The ability of Leishmania mexicana amazonensis to inhibit antigen specific T-cell proliferation against a non-parasite polypeptide antigen, poly(LTyr, LGlu)-poly(DLAla)–poly(LLys), was examined. Infection of mouse peritoneal macrophages by promastigotes blocked the proliferation of the T-cell line, TPB1. This effect was correlated with the level of parasite infection, and the timing of macrophage infection and antigen addition. Peritoneal macrophages from both BALB/b and C57BL/6 mice showed reduced ability to serve as antigen presenting cells.     

几种利什曼抗原对草原兔尾鼠婴儿利什曼原虫实验感染的保护作用

本项研究旨在确定几种利什曼表现分子抗原对婴儿利什曼原虫实验感染的免疫保护作用。用重组的利什曼原虫细胞表现糖蛋白ＧＰ６３和脂磷酸聚糖（ＬＰＧ）以短小棒状杆菌菌苗为佐剂免疫草原兔尾鼠。用婴儿利什曼原母亲朱前鞭毛体攻击感染,测定其免疫保护作用。经ｒＧＰ６３＋ＬＰＧ＋ＣＰ免疫的动物,在用２×１０＾２前鞭毛体攻击时,其肝脏的利什曼原虫数比对照动物降低８９．７９％。ＬＰＧ＋ＣＰ免疫组降低６０．６％,ｒＧＰ６３     

胶体金标记杜氏利什曼原虫抗原超微结构定位研究

用低温包埋剂Lowicry1 K4M在-30℃下包埋杜氏利什曼原虫前鞭毛体,切片后在电镜下观察到前鞭毛体结构保存较好。用单克隆抗体2H_6-E_5和1H_7-C_2-E_7分别对它们所识别的杜氏利什曼原虫前鞭毛体抗原进行胶体金标记定位,结果发现保护性抗体2H_6-E_3识别的抗原主要分布于前鞭毛体膜外侧面,为进一步研究该抗原的组成、性质和功能建立了一定基础。同时发现1H_7-C_2-E_7识别的抗原主要分布于前鞭毛体膜内侧面,膜外侧面也有分布。     

The scavenger receptor MARCO is involved in Leishmania major infection by CBA/J macrophages

CBA/J mice are resistant to Leishmania major infection but are permissive to L. amazonensis infection. In addition, CBA/J macrophages control L. major but not L. amazonensis infection in vitro . Phagocytosis by macrophages is known to determine the outcome of Leishmania infection. Pattern recognition receptors (PRR) adorning antigen presenting cell surfaces are known to coordinate the link between innate and adaptive immunity. The macrophage receptor with collagenous structure (MARCO) is a PRR that is preferably expressed by macrophages and is capable of binding Gram-positive and Gram-negative bacteria. No research on the role of MARCO in Leishmania –macrophage interactions has been reported. Here, we demonstrate, for the first time, that MARCO expression by CBA/J macrophages is increased in response to both in vitro and in vivo L. major infections, but not to L. amazonensis infection. In addition, a specific anti-MARCO monoclonal antibody reduced L. major infection of macrophages by 30%–40% in vitro . The draining lymph nodes of anti-MARCO-treated mice displayed a reduced presence of immunolabelled parasite and parasite antigens, as well as a reduced inflammatory response. These results support the hypothesis that MARCO has a role in macrophage infection by L. major in vitro as well as in vivo.     

不同种株利什曼原虫的比较蛋白质组学分析

目的观察不同种株利什曼原虫前鞭毛体蛋白质表达状况。方法制备杜氏利什曼原虫四川SC6株、杜氏利什曼原虫四川SC10株和硕大利什曼原虫5ASKH株前鞭毛体总蛋白,以pH范围3-10的预制胶条进行双向电泳(2-D),考马斯亮蓝染色,PDQust软件分析凝胶,主要差异蛋白点用电喷雾质谱法进行鉴定。结果等量的杜氏利什曼原虫四川SC6株、杜氏利什曼原虫四川SC10株和硕大利什曼原虫5ASKH株前鞭毛体总蛋白均获近700个蛋白点,不同种株利什曼原虫前鞭毛体蛋白质2-D图谱中,14蛋白点呈恒定差异表达,从中鉴定出10个功能明确的蛋白质,分别具有下列生物功能:糖代谢与磷脂合成(烯醇酶、变旋酶、NADP依耐乙醇脱氢酶、乙醇胺磷酸胞苷酸转移酶),压力反应(细胞内过氧化物酶、锥虫还原蛋白过氧化物酶),细胞膜/细胞骨架(α-微管蛋白、β-微管蛋白),核酸代谢(琥珀酰辅酶A连接酶(GDP形成)、内源性RNA酶L-PSP(pb5)),细胞周期与增殖(延伸因子2)。结论不同种株利什曼原虫前鞭毛体蛋白质的表达存在不同,为理解不同种株利什曼原虫的毒力、免疫原性和代谢特征提供了新的视角。     

RT-PCR检测亚马孙利什曼原虫P-4和GP-46基因表达

目的 证明亚马孙利什曼原虫前鞭毛体和无鞭毛体的基因表达水平。 方法 用RNA分离试剂盒，分别提取3种不同来源的无鞭毛体（由小鼠模型皮损组织获得的无鞭毛体、由前鞭毛体培养转化而来的无鞭毛体, 以及来自J774.G8巨噬细胞株的无鞭毛体）的总RNA，以及前鞭毛体总RNA，然后用SuperScripⅡ逆转录聚合酶将其逆转录为cD-NA，再经PCR扩增无鞭毛体特异核酸酶（P-4）和前鞭毛体特异膜糖蛋白（GP-46）的特异片段，经1.5% 琼脂糖凝胶电泳分析。 结果 3种不同来源的无鞭毛体均观察到P-4特异性条带（273 bp），且密度相似，但在前鞭毛体中未观察到; 在前鞭毛体中观察到高表达的GP-46特异性条带（325 bp），但在3种无鞭毛体中弱表达。 结论 由前鞭毛体转化的无鞭毛体能高水平表达亚马孙利什曼原虫无鞭毛体P-4特异基因，可为其生物化学及免疫学研究提供无鞭毛体来源。     

Antileishmanial activity of azithromycin against Leishmania (Leishmania) amazonensis, Leishmania (Viannia) braziliensis, and Leishmania (Leishmania) chagasi

Azithromycin, an azalide antibiotic, is highly concentrated within different phagocytic cells, especially macrophages. The potential antileishmanial activity of azithromycin against three species of Leishmania from the New World was assessed using in vitro models. Azithromycin decreased viability of promastigote cultures of Leishmania (Leishmania) amazonensis, Leishmania (Viannia) braziliensis, and Leishmania (Leishmania) chagasi as determined by the colorimetric Alamar blue assay. In amastigote intracellular cultures, a significant decrease in infected macrophages counts was observed for all three species with IC(50) of 20.83 (27 micromol/L), 2.18 (2.7 micromol/L), and 6.12 (7.8 micromol/L) microg/mL, respectively. Azithromycin showed in vitro activity against L. (L.) amazonensis, L. (V.) braziliensis, and L. (L.) chagasi and may offer an alternative to current leishmaniasis treatment.     

亚马逊利什曼原虫无鞭毛体蛋白基因的克隆化与序列分析

目的：克隆亚马逊利什曼原虫（L.ama)无鞭毛蛋白（amastin)的编码基因,并对其同源基因序列进行分析,方法：根据我们首次克隆的硕大利什曼原虫（L.major)无鞭毛体蛋白的编码基因,设计并合成核苷酸序列特异性引物,以亚马逊利什曼原虫基因组DNA为模板,以多聚酶链反应PCR技术扩增无鞭毛体的编码基因DNA片段,并进行核苷酸 列测定以及核苷酸序列的同源性分析。结果：克隆了亚马逊利什曼原虫无鞭毛体蛋白的编码基因,含有单一开放读框,长度为552bp,编码的无鞭毛体蛋白由183个氨基酸残基（aa)组成,亚马逊利什曼原虫与硕大利什曼原虫无鞭毛体蛋白编码基因之间高度同源,在核苷酸与氨基酸残基序列水平上的同源性分别为96％和94％,结论：首次实现亚马逊利什曼原虫无鞭毛体蛋白基因的克隆化。     

The pharmacological inhibition of sterol biosynthesis in Leishmania is counteracted by enhancement of LDL endocytosis

Leishmania parasites, despite being able to synthesize their own sterols, acquire and accumulate significant amounts of cholesterol through low density lipoprotein (LDL) particle endocytosis. The role of this system in Leishmania amazonensis promastigotes under pharmacological pressure by sterol biosynthesis inhibitors (SBIs) was investigated. First, thin layer chromatography demonstrated that L. amazonensis promastigotes, in response to ergosterol biosynthesis inhibition by treatment with 4.0 and 6.0 μM ketoconazole or miconazole, accumulate up to two times more cholesterol than controls. The treatment of promastigotes with ketoconazole and simvastatin, two SBIs with non-related mechanisms of action, showed that both drugs induce increases in (125)I-LDL endocytosis in a dose-dependent manner, indicating that the accumulation of exogenous cholesterol is due to the enhancement of LDL uptake. Finally, it was demonstrated that L. amazonensis promastigotes were rendered more susceptible to treatment with SBIs (ketoconazole, miconazole, simvastatin and terbinafine) in the absence of exogenous cholesterol sources, with a reduction of the IC50s of about 50% in three of the four tested drugs. These results show that the exogenous cholesterol uptake system in L. amazonensis plays a role as a compensatory mechanism in response to the presence of SBIs, suggesting that it may be a potential pharmacological target.     

克拉玛依地区的利什曼病 Ⅸ.白蛉自然感染前鞭毛体的鉴定

本文报道新疆克拉玛依地区的大沙鼠洞、旷野及人房等不同场所内白蛉自然感染利什曼原虫的情况、蛉体内原虫对实验动物的致病特征以及用利什曼原虫McAb的dot-ELISA法对白蛉自然感染的利什曼前鞭毛体的检测结果;并结合4年来对当地白蛉的生态和大沙鼠体内的利什曼原虫对白蛉的感染性等一系列的调查研究,证实蒙古白蛉和安氏白蛉为克拉玛依大沙鼠体内利什曼原虫的传播媒介。     

利什曼原虫抗原对草原兔尾鼠感染婴儿利什曼原虫的免疫保护作用

目的： 测定利什曼原虫主要表面分子抗原对内脏利什曼病的免疫保护作用。方法： 用重组利什曼原虫表面糖蛋白ｒ Ｇ Ｐ６３ 和脂磷酸聚糖（ Ｌ Ｐ Ｇ） 为抗原, 以短棒状杆菌菌苗（ Ｃ Ｐ） 为佐剂免疫草原兔尾鼠后, 用婴儿利什曼原虫强毒株攻击, 观察免疫保护效果。结果： ｒ Ｇ Ｐ６３ 加 Ｌ Ｐ Ｇ 加 Ｃ Ｐ 抗原组合免疫后用２ ×１０７ 前鞭毛体攻击, 免疫动物的肝印片上 Ｌ Ｄ 数量明显降低, 减虫率为８９８ ％ 。 Ｌ Ｐ Ｇ 加 Ｃ Ｐ 免疫组减虫率为６０６ ％ 。ｒ Ｇ Ｐ６３ 包涵体加 Ｃ Ｐ 免疫组减虫率为４２４ ％ , 而纯化ｒ Ｇ Ｐ６３ 加 Ｃ Ｐ 免疫组未显示保护作用。以ｒ Ｇ Ｐ６３ 加 Ｌ Ｐ Ｇ 加 Ｃ Ｐ 免疫后用１ ×１０６ , ５ ×１０６ 和１ ×１０７ 前鞭毛体攻击时, 感染率亦有明显降低。结论： 利什曼原虫主要表面分子抗原 Ｇ Ｐ６３和 Ｌ Ｐ Ｇ 在以 Ｃ Ｐ 为佐剂的条件下, 对草原兔尾鼠婴儿利什曼原虫有明显的免疫保护效果。     

Differentiation of old and new world leishmania species at complex and species levels by PCR

The variable and conserved sequence boxes of kinetoplast DNA (kDNA) of 11 standard strains of 6 complexes of New and Old World Leishmania were amplified using PCR. Four strains from 2 complexes of Old World Leishmania - L. major (MRHO/IR/64/Nadim-1), with 2 bands at 850 and 620 bp, L. major (MHOM/SU/73/5-ASKH), with a band at 620 bp, L. donovani, with a band at 800 bp and L. infantum, with a band at 650 bp - could be differentiated from each other and from the New World strains, with the exception of L. infantum. Seven Leishmania strains from 4 complexes of New World Leishmania - L. mexicana and L. pifanoi, with a band at 730 bp, L. guyanensis, with 2 bands at 730 and 650 bp, L. peruviana, with a band at 710 bp and L. amazonensis, L. garnhami and L. braziliensis, each with a band at 650 bp - were identified. Of these strains, L. guyanensis and L. peruviana could be differentiated from each other and from the Old World strains. These results show that using PCR amplification of kDNA we could differentiate between New and Old World Leishmania at both complex and strain levels. The amplified kDNA PCR products, together with other techniques, could be useful as a diagnostic tool for the identification of Leishmania species.     

Molecular cloning and characterization of the immunologically protective surface glycoprotein GP46/M-2 of Leishmania amazonensis.

Immunization of mice with the GP46/M-2 membrane glycoprotein has been demonstrated to elicit protection against infection with the parasitic protozoan Leishmania amazonensis. As this molecule is important for future vaccine studies of leishmaniasis, the gene encoding the GP46/M-2 surface membrane glycoprotein of Leishmania amazonensis has been cloned and sequenced. The protein sequence derived from the DNA sequence data is consistent with the known biochemical and immunochemical properties of the protein and indicates a number of structural areas of interest. A repetitive sequence (24 amino acids repeated four times) occurs within the amino-terminal portion of the molecule and constitutes approximately 22% of the total mature protein. The protease-resistant immunodominant carboxyl-terminal domain of the protein comprises approximately half of the molecule and consists of proline-rich and cysteine-rich areas of sequence; the distribution of cysteine residues is suggestive of metal binding motifs. The sequence predicts a hydrophobic leader peptide, and a putative attachment site for a glycosyl-phosphatidylinositol anchor is indicated at the carboxyl terminus, consistent with the membrane location of the protein. Southern blot analyses also indicate the presence of a GP46/M-2 gene family.     

Destruction of Leishmania mexicana amazonensis promastigotes by normal human serum

Fresh normal human serum was observed to have a lethal effect on Leishmania mexicana amazonensis promastigotes obtained from laboratory-bred Lutzomyia longipalpis or on promastigotes grown in liquid culture medium, inoculated with the same isolates. Heat inactivation abolished the Leishmania lytic activity from the sera. Resistance of culture promastigotes to lysis by normal human serum was investigated in three isolates of L. m. amazonensis. Development of resistance (up to 7%) was found in only one isolate, obtained from the bone marrow in a human case of visceral leishmaniasis.