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Tawfeeq HM, Ali SA. Molecular-based assay for genotyping Leishmania spp. from clinically suspected cutaneous leishmaniasis lesions in the Garmian area, Kurdistan Region of Iraq. Parasite Epidemiol Control 2022; 17:e00240. [PMID: 35141432 PMCID: PMC8810569 DOI: 10.1016/j.parepi.2022.e00240] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/25/2021] [Accepted: 01/18/2022] [Indexed: 11/16/2022] Open
Affiliation(s)
- Hassan Mohammad Tawfeeq
- Nursing Department, Kalar Technical College, Sulaimani Polytechnic University, Sulaimani 46001 Kalar, Kurdistan Region, Iraq
- Department of Microbiology, College of Medicine, University of Sulaimani, Kurdistan Region, Iraq
- Corresponding author at: Nursing Department, Kalar Technical College, Sulaimani Polytechnic University, 46001 Kalar, Kurdistan Region, Iraq.
| | - Shahnaz AbdulKader Ali
- Department of Microbiology, College of Medicine, University of Sulaimani, Kurdistan Region, Iraq
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Phenotypical and genotypical differences among Leishmania (Leishmania) amazonensis isolates that caused different clinical frames in humans and dogs: A systematic review. Acta Trop 2021; 221:106018. [PMID: 34157292 DOI: 10.1016/j.actatropica.2021.106018] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 06/15/2021] [Accepted: 06/15/2021] [Indexed: 11/23/2022]
Abstract
Leishmania (Leishmania) amazonensis is an important etiological agent of American cutaneous leishmaniasis (ACL) in Brazil. The species causes a large spectrum of clinical manifestations in humans and dogs, ranging from cutaneous, cutaneous diffuse, mucocutaneous, and visceral involvement, however, the factors that drive the development of different disease forms by the same species are not yet fully known. In the present work, it was systematically reviewed the studies addressing phenotypic and genotypic characteristics of Leishmania (L.) amazonensis isolates causing cutaneous and visceral clinical frames in humans and dogs, comparing the results observed. For this, four research databases were searched for the following keywords: (Leishmania amazonensis AND visceral leishmaniasis) AND (tropism OR virulence OR visceralization OR adaptations OR mutation OR clinical presentation OR resistance OR survival OR wide spectrum). The results revealed that the complexity disease seems to involve the combination of genetic factors of the parasite (as modifications in molecules related to the virulence and metabolism) and also of the host's immune background and status. Nonetheless, the exact mechanism that leads to different clinical manifestations between strains of the same species is still uncertain and future studies must be developed to better elucidate this phenomenon.
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Mirahmadi H, Rezaee N, Mehravaran A, Heydarian P, Raeghi S. Detection of species and molecular typing of Leishmania in suspected patients by targeting cytochrome b gene in Zahedan, southeast of Iran. Vet World 2018; 11:700-705. [PMID: 29915511 PMCID: PMC5993770 DOI: 10.14202/vetworld.2018.700-705] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 04/23/2018] [Indexed: 11/16/2022] Open
Abstract
Aim: Cutaneous leishmaniasis (CL) is one of the most important health problems that are capable of involving both tropical and subtropical areas, especially in Iran. This cross-sectional study aimed to differentiate the species that are able to cause CL in Zahedan city by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Materials and Methods: It was conducted on 145 suspected CL patients in Zahedan city between 2014 and 2016. The smears were initially prepared, air-dried, fixed with absolute methanol, and stained with 10% Giemsa. Then, we examined the stained samples by a light microscope under 1000× magnifications. PCR assay targeted cytochrome b(cyt b) gene using LCBF1 and LCBR2 primers and the products digested by Ssp1 enzymes. Results: From 145 suspected CL patients, 76 (52.4%) were positive in microscopic examination. In addition, we detected gene of interest (cyt b) in 98 (67.5%). The results of PCR-RFLP indicated that 53/98 (54%) cases were Leishmania major and 45/98 (46%) were Leishmania tropica, and the main species in these areas was L. major. Conclusion: We concluded that the microscopic examination is not sensitive enough and is not able to distinguish between different Leishmania species. Instead, molecular methods like PCR-RFLP can be appropriately used with promising results.
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Affiliation(s)
- Hadi Mirahmadi
- Infectious Diseases and Tropical Medicine Research Center, Zahedan University of Medical Sciences, Zahedan, Iran.,Department of Parasitology and Mycology, Faculty of Medicine, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Nasrin Rezaee
- Infectious Diseases and Tropical Medicine Research Center, Zahedan University of Medical Sciences, Zahedan, Iran.,Department of Parasitology and Mycology, Faculty of Medicine, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Ahmad Mehravaran
- Infectious Diseases and Tropical Medicine Research Center, Zahedan University of Medical Sciences, Zahedan, Iran.,Department of Parasitology and Mycology, Faculty of Medicine, Zahedan University of Medical Sciences, Zahedan, Iran
| | - Peyman Heydarian
- Department of Medical Parasitology and Mycology, School of Medicine, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Saber Raeghi
- Department of Laboratory Sciences, Maragheh University of Medical Sciences, Maragheh, Iran
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4
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Abstract
Leishmania is an infectious protozoan parasite related to African and American trypanosomes. All Leishmania species that are pathogenic to humans can cause dermal disease. When one is confronted with cutaneous leishmaniasis, identification of the causative species is relevant in both clinical and epidemiological studies, case management, and control. This review gives an overview of the currently existing and most used assays for species discrimination, with a critical appraisal of the limitations of each technique. The consensus taxonomy for the genus is outlined, including debatable species designations. Finally, a numerical literature analysis is presented that describes which methods are most used in various countries and regions in the world, and for which purposes.
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Affiliation(s)
- Gert Van der Auwera
- Institute of Tropical Medicine, Department of Biomedical Sciences, Antwerp, Belgium
| | - Jean-Claude Dujardin
- Institute of Tropical Medicine, Department of Biomedical Sciences, Antwerp, Belgium Antwerp University, Department of Biomedical Sciences, Antwerp, Belgium
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5
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Goto H, Lindoso JAL. Current diagnosis and treatment of cutaneous and mucocutaneous leishmaniasis. Expert Rev Anti Infect Ther 2014; 8:419-33. [DOI: 10.1586/eri.10.19] [Citation(s) in RCA: 287] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Comparative analyses of the β-tubulin gene and molecular modeling reveal molecular insight into the colchicine resistance in kinetoplastids organisms. BIOMED RESEARCH INTERNATIONAL 2013; 2013:843748. [PMID: 24083244 PMCID: PMC3780476 DOI: 10.1155/2013/843748] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 07/16/2013] [Indexed: 11/20/2022]
Abstract
Differential susceptibility to microtubule agents has been demonstrated between mammalian cells and kinetoplastid organisms such as Leishmania spp. and Trypanosoma spp. The aims of this study were to identify and characterize the architecture of the putative colchicine binding site of Leishmania spp. and investigate the molecular basis of colchicine resistance. We cloned and sequenced the β-tubulin gene of Leishmania (Viannia) guyanensis and established the theoretical 3D model of the protein, using the crystallographic structure of the bovine protein as template. We identified mutations on the Leishmania
β-tubulin gene sequences on regions related to the putative colchicine-binding pocket, which generate amino acid substitutions and changes in the topology of this region, blocking the access of colchicine. The same mutations were found in the β-tubulin sequence of kinetoplastid organisms such as Trypanosoma cruzi, T. brucei, and T. evansi. Using molecular modelling approaches, we demonstrated that conformational changes include an elongation and torsion of an α-helix structure and displacement to the inside of the pocket of one β-sheet that hinders access of colchicine. We propose that kinetoplastid organisms show resistance to colchicine due to amino acids substitutions that generate structural changes in the putative colchicine-binding domain, which prevent colchicine access.
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7
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Intraspecific variability in several isolates of Philasterides dicentrarchi (syn. Miamiensis avidus), a scuticociliate parasite of farmed turbot. Vet Parasitol 2011; 175:260-72. [DOI: 10.1016/j.vetpar.2010.10.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 09/28/2010] [Accepted: 10/08/2010] [Indexed: 11/23/2022]
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In vitro activities of ER-119884 and E5700, two potent squalene synthase inhibitors, against Leishmania amazonensis: antiproliferative, biochemical, and ultrastructural effects. Antimicrob Agents Chemother 2008; 52:4098-114. [PMID: 18765694 DOI: 10.1128/aac.01616-07] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ER-119884 and E5700, novel arylquinuclidine derivatives developed as cholesterol-lowering agents, were potent in vitro growth inhibitors of both proliferative stages of Leishmania amazonensis, the main causative agent of cutaneous leishmaniasis in South America, with the 50% inhibitory concentrations (IC(50)s) being in the low-nanomolar to subnanomolar range. The compounds were very potent noncompetitive inhibitors of native L. amazonensis squalene synthase (SQS), with inhibition constants also being in the nanomolar to subnanomolar range. Growth inhibition was strictly associated with the depletion of the parasite's main endogenous sterols and the concomitant accumulation of exogenous cholesterol. Using electron microscopy, we identified the intracellular structures affected by the compounds. A large number of lipid inclusions displaying different shapes and electron densities were observed after treatment with both SQS inhibitors, and these inclusions were associated with an intense disorganization of the membrane that surrounds the cell body and flagellum, as well as the endoplasmic reticulum and the Golgi complex. Cells treated with ER-119884 but not those treated with E5700 had an altered cytoskeleton organization due to an abnormal distribution of tubulin, and many were arrested at cytokinesis. A prominent contractile vacuole and a phenotype typical of programmed cell death were frequently found in drug-treated cells. The selectivity of the drugs was demonstrated with the JC-1 mitochondrial fluorescent label and by trypan blue exclusion tests with macrophages, which showed that the IC(50)s against the host cells were 4 to 5 orders of magnitude greater that those against the intracellular parasites. Taken together, our results show that ER-119884 and E5700 are unusually potent and selective inhibitors of the growth of Leishmania amazonensis, probably because of their inhibitory effects on de novo sterol biosynthesis at the level of SQS, but some of our observations indicate that ER-119884 may also interfere with other cellular processes.
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9
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Sukmee T, Siripattanapipong S, Mungthin M, Worapong J, Rangsin R, Samung Y, Kongkaew W, Bumrungsana K, Chanachai K, Apiwathanasorn C, Rujirojindakul P, Wattanasri S, Ungchusak K, Leelayoova S. A suspected new species of Leishmania, the causative agent of visceral leishmaniasis in a Thai patient. Int J Parasitol 2008; 38:617-22. [DOI: 10.1016/j.ijpara.2007.12.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Accepted: 12/28/2007] [Indexed: 10/22/2022]
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10
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Leishmania amazonensis: humoral response to amastigote excreted-antigens in murine leishmaniasis. Exp Parasitol 2007; 116:492-6. [PMID: 17349625 DOI: 10.1016/j.exppara.2007.01.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 01/06/2007] [Accepted: 01/24/2007] [Indexed: 11/19/2022]
Abstract
With the purpose of studying the antigenic role that factors excreted by Leishmania amastigotes might have during murine infection, immunoblots were carried out with sera from C57BL/6 and BALB/c mice infected with two strains of Leishmania (L.) amazonensis, NR and IFLA/BR. Both strains differ widely in virulence in BALB/c mice. BALB/c but not C57BL/6 sera recognized several excretion products. The excreted antigens showed a strong response towards IgG1 and IgG2a isotypes whilst they reacted only weakly against IgG2b and IgG3. A low-molecular weight antigen (about 20 kDa) excreted by both Leishmania strains was strongly recognized by IgG1 from BALB/c mice sera infected with IFLA/BR, the most virulent strain. Sera from NR infected mice were incapable of recognizing this antigen in spite of its presence in NR excreted products. The results indicate that the humoral immune response to excreted antigens of amastigotes depends on both the host genetic background and the parasite strain.
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11
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Uzcategui NL, Figarella K, Camacho N, Ponte-Sucre A. Substrate preferences and glucose uptake in glibenclamide-resistant Leishmania parasites. Comp Biochem Physiol C Toxicol Pharmacol 2005; 140:395-402. [PMID: 15886061 DOI: 10.1016/j.cca.2005.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2004] [Revised: 03/28/2005] [Accepted: 04/01/2005] [Indexed: 11/23/2022]
Abstract
Several drug-resistant mammalian cell types exhibit increased glycolytic rates, preferential synthesis of ATP through oxidative phosphorylation, and altered glucose transport. Herein we analyzed the influence of parasite growth phase on energy substrate uptake and use in a Leishmania strain [NR(Gr)] selected for resistance against glibenclamide. Glibenclamide is an ABC-transporter blocker which modulates the function of glucose transporters in some mammalian cells. Our results demonstrate for the first time that compared to glibenclamide-sensitive Leishmania, exponential phase glibenclamide-resistant parasites exhibit decreased use of glucose as energy substrate, decreased glucose uptake and decreased glucose transporter expression. However, compared to glibenclamide-sensitive cells, stationary phase resistant parasites display an increased use of amino acids as energy substrate and an increased activity of the enzymes hexokinase, phosphoglucose isomerase, and especially NAD(+)-linked glutamate dehydrogenase. These results suggest that drug resistance in Leishmania involves a metabolic adaptation that promotes a stage dependent modulation of energy substrate uptake and use as a physiological response to the challenge imposed by drug pressure.
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Affiliation(s)
- Nestor Luis Uzcategui
- Laboratorio de Fisiología Molecular, Instituto de Medicina Experimental, Facultad de Medicina, Universidad Central de Venezuela, Caracas, Venezuela
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12
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Silva N, Camacho N, Figarella K, Ponte-Sucre A. Cell differentiation and infectivity ofLeishmania mexicanaare inhibited in a strain resistant to an ABC-transporter blocker. Parasitology 2004; 128:629-34. [PMID: 15206465 DOI: 10.1017/s0031182004005098] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We analysed whether markers of cell differentiation and infectivity differed when compared to the parental sensitive strain [NR(Gs)] in anin vitroselectedLeishmaniastrain [NR(Gr)] resistant to Glibenclamide®, an ATP-binding-cassette (ABC)-transporter blocker. The data show that the cell body area was larger in NR(Gr) compared to NR(Gs) and that functional characters associated with an infective metacyclic phenotype, such as resistance to the lytic effect of the alternative complement pathway and expression of the Meta-1 protein, were reduced. The infectivity of NR(Gr) to J774.1 macrophages was also significantly reduced. These results suggest that resistance inLeishmaniaagainst Glibenclamide®, a general blocker of P-glycoproteins, could produce functional modifications that may be relevant forLeishmaniadifferentiation, infectivity and survival.
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Affiliation(s)
- N Silva
- Laboratory of Molecular Physiology, Instituto de Medicina Experimental, Facultad de Medicina, Universidad Central de Venezuela, Caracas, Venezuela
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13
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Marfurt J, Nasereddin A, Niederwieser I, Jaffe CL, Beck HP, Felger I. Identification and differentiation of Leishmania species in clinical samples by PCR amplification of the miniexon sequence and subsequent restriction fragment length polymorphism analysis. J Clin Microbiol 2003; 41:3147-53. [PMID: 12843055 PMCID: PMC165364 DOI: 10.1128/jcm.41.7.3147-3153.2003] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We recently developed a new PCR-restriction fragment length polymorphism (RFLP)-based assay using the miniexon sequence from the genus Leishmania. Here we report the application of this new genotyping method to naturally infected clinical samples for the differentiation of New and Old World Leishmania species. Of the newly developed assay and four currently applied diagnostic tests (i.e., in vitro cultivation, serology, and two other molecular assays using either the small subunit-internal transcribed spacer sequence or a repetitive genomic sequence), the miniexon assay showed the highest sensitivity, 89.7%, compared to 70.6, 57.1, 51.7, and 79.3%, respectively. Species differentiation was robust and reliable compared with that by two other Leishmania genotyping techniques. The assay provides a valuable tool for the identification of Leishmania directly from clinical samples and enables determination of the infecting species by a facile technique with high discrimination power. Since Leishmania causes a broad spectrum of diseases distinguished by different parasite and host factors, detection and characterization of the infecting species is crucial for the confirmation of a diagnosis as well as the establishment of the clinical prognosis and the initiation of an adequate therapeutic approach. The miniexon PCR-RFLP assay will facilitate such determination and might improve diagnosis and treatment of leishmaniasis.
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Affiliation(s)
- Jutta Marfurt
- Department of Medical Parasitology and Infection Biology, Swiss Tropical Institute, Basel, Switzerland
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Marfurt J, Niederwieser I, Makia ND, Beck HP, Felger I. Diagnostic genotyping of Old and New World Leishmania species by PCR-RFLP. Diagn Microbiol Infect Dis 2003; 46:115-24. [PMID: 12812715 DOI: 10.1016/s0732-8893(03)00040-3] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We have designed a new genotyping scheme for molecular diagnosis of the different Leishmania species pathogenic to humans. This scheme is based on PCR amplified sequences from the gene for the spliced leader RNA (mini-exon). This target was selected because it is present as tandem repeats (100 to 200 copies) in the genus Leishmania and other kinetoplastida, but is absent from the mammalian hosts and the sandfly vectors. The exon is highly conserved, whereas the intron and non-transcribed spacer region vary in size and sequence among different species. Thus, it was possible to amplify DNA from both Old and New World pathogenic Leishmania complexes using a single pair of primers deriving from the conserved region of the mini-exon tandem repeat. Species identification was performed by digesting mini-exon PCR products with one or two different restriction enzymes. Restriction fragment length polymorphism (RFLP) generated species-specific patterns of bands visualized in agarose gels, which allowed to differentiate each species unequivocally.
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Affiliation(s)
- Jutta Marfurt
- Department of Medical Parasitology and Infection Biology, Swiss Tropical Institute, Basel, Switzerland
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15
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Akman L, Aksu HS, Wang RQ, Ozensoy S, Ozbel Y, Alkan Z, Ozcel MA, Culha G, Ozcan K, Uzun S, Memisoglu HR, Chang KP. Multi-site DNA polymorphism analyses of Leishmania isolates define their genotypes predicting clinical epidemiology of leishmaniasis in a specific region. J Eukaryot Microbiol 2000; 47:545-54. [PMID: 11128706 DOI: 10.1111/j.1550-7408.2000.tb00088.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Leishmania isolates from 57 cases of human cutaneous (CL), human visceral (VL), and canine visceral (CVL) leishmaniasis in Turkey were grouped by multi-site DNA polymorphism analyses into five genotypes. The initial grouping was based on DNA heterogeneity of the faster-evolving mitochondrion (kinetoplast) minicircles and the intergenic regions of two nuclear repetitive genes. Taxonomic affiliation and phylogenetic relationships of the five genotypes were inferred by comparing them with reference species for sequence heterogeneity in a approximately 1.4 kb conserved single-copy gene, encoding N-acetylglucosamine-1-phosphate transferase (NAGT). Alignment of the available sequences revealed no gap, but up to 7% scattered base substitutions, suggesting that this functionally important gene is a suitable marker. Three genotypes are completely identical to the NAGTs of the reference species, identifying them as L. infantum, L. tropica. and L. major, respectively. The remaining two are recognized as L. major NAGT variants with one and four base substitutions, respectively. As expected, Maximum Likelihood analysis of the NAGT sequences separates them into three clades, corresponding to the three species. The majority of the isolates obtained are L. infantum and L. tropica, which have been known to cause infantile VL and anthroponotic CL in western and southeastern Turkey, respectively. Unexpected is the finding of Leishmania major variants and their dispersal, possibly as previously unrecognized clinico-epidemiologic entities of CL and VL.
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MESH Headings
- Adolescent
- Adult
- Animals
- Base Sequence
- Child
- Child, Preschool
- DNA, Kinetoplast/analysis
- DNA, Kinetoplast/genetics
- DNA, Protozoan/analysis
- DNA, Protozoan/genetics
- Dogs
- Female
- Genotype
- Humans
- Infant
- Leishmania/classification
- Leishmania/genetics
- Leishmania infantum/classification
- Leishmania infantum/genetics
- Leishmania major/classification
- Leishmania major/genetics
- Leishmania tropica/classification
- Leishmania tropica/genetics
- Leishmaniasis, Cutaneous/epidemiology
- Leishmaniasis, Cutaneous/parasitology
- Leishmaniasis, Visceral/epidemiology
- Leishmaniasis, Visceral/parasitology
- Male
- Metalloendopeptidases/genetics
- Molecular Sequence Data
- Polymerase Chain Reaction
- Polymorphism, Genetic
- Transferases (Other Substituted Phosphate Groups)/genetics
- Tubulin/genetics
- Turkey/epidemiology
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Affiliation(s)
- L Akman
- Department of Microbiology and Immunology, University of Health Sciences, Chicago Medical School, North Chicago, Illinois, 60064 USA
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Cacciò S, Cammà C, Onuma M, Severini C. The beta-tubulin gene of Babesia and Theileria parasites is an informative marker for species discrimination. Int J Parasitol 2000; 30:1181-5. [PMID: 11027785 DOI: 10.1016/s0020-7519(00)00105-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A fragment of the beta-tubulin gene was polymerase chain reaction (PCR) amplified from genomic DNAs of Babesia bovis, Babesia bigemina, Babesia divergens, Babesia major, Babesia caballi, Babesia equi, Babesia microti, Theileria annulata and Theileria sergenti. Single amplification products were obtained for each of these species, but the size of the amplicons varied from 310 to 460 bp. Sequence analysis revealed that this variation is due to the presence of a single intron, which ranged from 20 to 170 bp. The extensive genetic variability at the beta-tubulin locus has been exploited to develop two types of species identification assays. The first assay can be used on samples containing mostly parasite DNA, like those prepared from infected erythrocytes. Following PCR amplification, the species identification is obtained directly from the size of the products (for Babesia species infecting human or horse) or using a simple PCR-restriction fragment length polymorphism (RFLP) protocol (for Babesia species infecting cattle). The second assay can be used on samples prepared from whole blood, that contain both parasite and host DNAs. In this case, due to the strong conservation of the beta-tubulin gene, co-amplification of a gene fragment from the host DNA was observed. A nested PCR assay was developed for the specific amplification of parasite DNA, using a primer designed to span the exon-intron boundary. Direct identification of Babesia species infecting human and horse is again obtained after the electrophoretic separation of the amplification products, while for Babesia and Theileria species infecting cattle, differentiation is based on a nested PCR-RFLP protocol. These methods may be used for the simultaneous identification of horses and cattle carrying multiple parasites by means of a single PCR or using the PCR-RFLP protocol.
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Affiliation(s)
- S Cacciò
- Laboratory of Parasitology, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy.
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