WorldWideScience

Sample records for apicoplasts

  1. Apicoplast-Targeting Antibacterials Inhibit the Growth of Babesia Parasites

    OpenAIRE

    AbouLaila, Mahmoud; Munkhjargal, Tserendorj; SIVAKUMAR, Thillaiampalam; Ueno, Akio; Nakano, Yuki; Yokoyama, Miki; Yoshinari, Takeshi; NAGANO, Daisuke; Katayama, Koji; El-Bahy, Nasr; Yokoyama, Naoaki; Igarashi, Ikuo

    2012-01-01

    The apicoplast housekeeping machinery, specifically apicoplast DNA replication, transcription, and translation, was targeted by ciprofloxacin, thiostrepton, and rifampin, respectively, in the in vitro cultures of four Babesia species. Furthermore, the in vivo effect of thiostrepton on the growth cycle of Babesia microti in BALB/c mice was evaluated. The drugs caused significant inhibition of growth from an initial parasitemia of 1% for Babesia bovis, with 50% inhibitory concentrations (IC50s)...

  2. Anti-malarial Drug Design by Targeting Apicoplasts: New Perspectives

    Directory of Open Access Journals (Sweden)

    Avinaba Mukherjee

    2016-03-01

    Full Text Available Objectives: Malaria has been a major global health problem in recent times with increasing mortality. Current treatment methods include parasiticidal drugs and vaccinations. However, resistance among malarial parasites to the existing drugs has emerged as a significant area of concern in anti-malarial drug design. Researchers are now desperately looking for new targets to develop anti-malarials drug which is more target specific. Malarial parasites harbor a plastid-like organelle known as the ‘apicoplast’, which is thought to provide an exciting new outlook for the development of drugs to be used against the parasite. This review elaborates on the current state of development of novel compounds targeted againstemerging malaria parasites. Methods: The apicoplast, originates by an endosymbiotic process, contains a range of metabolic pathways and housekeeping processes that differ from the host body and thereby presents ideal strategies for anti-malarial drug therapy. Drugs are designed by targeting the unique mechanism of the apicoplasts genetic machinery. Several anabolic and catabolic processes, like fatty acid, isopenetyl diphosphate and heme synthess in this organelle, have also been targeted by drugs. Results: Apicoplasts offer exciting opportunities for the development of malarial treatment specific drugs have been found to act by disrupting this organelle’s function, which wouldimpede the survival of the parasite. Conclusion: Recent advanced drugs, their modes of action, and their advantages in the treatment of malaria by using apicoplasts as a target are discussed in this review which thought to be very useful in desigining anti-malarial drugs. Targetting the genetic machinery of apicoplast shows a great advantange regarding anti-malarial drug design. Critical knowledge of these new drugs would give a healthier understanding for deciphering the mechanism of action of anti-malarial drugs when targeting apicoplasts to overcome drug

  3. Selective inhibition of apicoplast tryptophanyl-tRNA synthetase causes delayed death in Plasmodium falciparum.

    Science.gov (United States)

    Pasaje, Charisse Flerida A; Cheung, Vanessa; Kennedy, Kit; Lim, Erin E; Baell, Jonathan B; Griffin, Michael D W; Ralph, Stuart A

    2016-01-01

    The malaria parasite Plasmodium falciparum relies on efficient protein translation. An essential component of translation is the tryptophanyl-tRNA synthetase (TrpRS) that charges tRNA(trp). Here we characterise two isoforms of TrpRS in Plasmodium; one eukaryotic type localises to the cytosol and a bacterial type localises to the remnant plastid (apicoplast). We show that the apicoplast TrpRS aminoacylates bacterial tRNA(trp) while the cytosolic TrpRS charges eukaryotic tRNA(trp). An inhibitor of bacterial TrpRSs, indolmycin, specifically inhibits aminoacylation by the apicoplast TrpRS in vitro, and inhibits ex vivo Plasmodium parasite growth, killing parasites with a delayed death effect characteristic of apicoplast inhibitors. Indolmycin treatment ablates apicoplast inheritance and is rescuable by addition of the apicoplast metabolite isopentenyl pyrophosphate (IPP). These data establish that inhibition of an apicoplast housekeeping enzyme leads to loss of the apicoplast and this is sufficient for delayed death. Apicoplast TrpRS is essential for protein translation and is a promising, specific antimalarial target. PMID:27277538

  4. Apicoplast Biosynthetic Pathways as Possible Targetsfor Combination Therapy of Malaria

    Institute of Scientific and Technical Information of China (English)

    Solomon Tesfaye; Bhanu Prakash; Prati Pal Singh

    2015-01-01

    The emergence of malaria parasite strains resistant to practically all the antimalarial drugs in clinical use is now making itnecessary to discover and develop both new antimalarial drugs and treatments. Recent advances in molecular techniques along withthe availability of genome sequence ofPlasmodiumfalciparum may provide a wide range of novel targets in metabolic pathways likeisoprenoid biosynthesis, fatty acid biosynthesis and heme biosynthesis in the apicoplast of Plasmodiurn. On the other hand, thecombination therapy approach (currently used to retard the selection of parasite strains resistant to individual components of acombination of drugs) has proved to be a success in the combination of sulphadoxine and pyrimethamine, which targets two differentsteps in the folate pathway of malaria parasite. However, after the success of this therapeutic combination, the efficacy of othercombinations of drugs which target different enzymes in a particular metabolic pathway has, apparently, not been reported. Therefore,herein, we review various drug targets so far discovered in apicoplast-related anabolic pathways, especially, with a sharper focus onthe possibility to target more than one enzyme at a time in a particular metabolic pathway of malaria parasites.

  5. Molecular phylogeny of Toxoplasmatinae: comparison between inferences based on mitochondrial and apicoplast genetic sequences

    OpenAIRE

    Michelle Klein Sercundes; Samantha Yuri Oshiro Branco Valadas; Lara Borges Keid; Tricia Maria Ferreira Souza Oliveira; Helena Lage Ferreira; Ricardo Wagner Almeida Vitor; Fábio Gregori; Rodrigo Martins Soares

    2016-01-01

    Abstract Phylogenies within Toxoplasmatinae have been widely investigated with different molecular markers. Here, we studied molecular phylogenies of the Toxoplasmatinae subfamily based on apicoplast and mitochondrial genes. Partial sequences of apicoplast genes coding for caseinolytic protease (clpC) and beta subunit of RNA polymerase (rpoB), and mitochondrial gene coding for cytochrome B (cytB) were analyzed. Laboratory-adapted strains of the closely related parasites Sarcocystis falcatula ...

  6. Role of Calcium Signaling in the Transcriptional Regulation of the Apicoplast Genome of Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Sabna Cheemadan

    2014-01-01

    Full Text Available Calcium is a universal second messenger that plays an important role in regulatory processes in eukaryotic cells. To understand calcium-dependent signaling in malaria parasites, we analyzed transcriptional responses of Plasmodium falciparum to two calcium ionophores (A23187 and ionomycin that cause redistribution of intracellular calcium within the cytoplasm. While ionomycin induced a specific transcriptional response defined by up- or downregulation of a narrow set of genes, A23187 caused a developmental arrest in the schizont stage. In addition, we observed a dramatic decrease of mRNA levels of the transcripts encoded by the apicoplast genome during the exposure of P. falciparum to both calcium ionophores. Neither of the ionophores caused any disruptions to the DNA replication or the overall apicoplast morphology. This suggests that the mRNA downregulation reflects direct inhibition of the apicoplast gene transcription. Next, we identify a nuclear encoded protein with a calcium binding domain (EF-hand that is localized to the apicoplast. Overexpression of this protein (termed PfACBP1 in P. falciparum cells mediates an increased resistance to the ionophores which suggests its role in calcium-dependent signaling within the apicoplast. Our data indicate that the P. falciparum apicoplast requires calcium-dependent signaling that involves a novel protein PfACBP1.

  7. Phylogenetic analyses suggest lateral gene transfer from the mitochondrion to the apicoplast

    Czech Academy of Sciences Publication Activity Database

    Oborník, Miroslav; Van de Peer, Y.; Hypša, Václav; Frickey, T.; Šlapeta, Jan Roger; Meyer, A.; Lukeš, Julius

    2002-01-01

    Roč. 285, 1-2 (2002), s. 109-118. ISSN 0378-1119 R&D Projects: GA AV ČR IAB5022904; GA AV ČR IAA6022903 Institutional research plan: CEZ:AV0Z6022909 Keywords : apicoplast * mitochondrion * hybrid genome Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.778, year: 2002

  8. Evolution of the apicoplast and its hosts: from heterotrophy to autotrophy and back again

    Czech Academy of Sciences Publication Activity Database

    Oborník, Miroslav; Janouškovec, Jan; Chrudimský, Tomáš; Lukeš, Julius

    2009-01-01

    Roč. 39, č. 1 (2009), s. 1-12. ISSN 0020-7519 R&D Projects: GA ČR GA206/06/1439 Institutional research plan: CEZ:AV0Z60220518 Keywords : Apicoplast * Apicomplexan * evolution * Chromera velia * GAPDH Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.819, year: 2009

  9. Notes on coccidian phylogeny, based on the apicoplast small subunit ribosomal DNA

    Czech Academy of Sciences Publication Activity Database

    Oborník, Miroslav; Jirků, Milan; Šlapeta, Jan Roger; Modrý, David; Koudela, Břetislav; Lukeš, Julius

    2002-01-01

    Roč. 88, č. 4 (2002), s. 360-363. ISSN 0932-0113 R&D Projects: GA AV ČR IAB5022904 Institutional research plan: CEZ:AV0Z6022909 Keywords : coccidia * apicoplast * SSU rRNA Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.046, year: 2002

  10. Identification of vital and dispensable sulfur utilization factors in the Plasmodium apicoplast.

    Directory of Open Access Journals (Sweden)

    Joana M Haussig

    Full Text Available Iron-sulfur [Fe-S] clusters are ubiquitous and critical cofactors in diverse biochemical processes. They are assembled by distinct [Fe-S] cluster biosynthesis pathways, typically in organelles of endosymbiotic origin. Apicomplexan parasites, including Plasmodium, the causative agent of malaria, harbor two separate [Fe-S] cluster biosynthesis pathways in the their mitochondrion and apicoplast. In this study, we systematically targeted the five nuclear-encoded sulfur utilization factors (SUF of the apicoplast [Fe-S] cluster biosynthesis pathway by experimental genetics in the murine malaria model parasite Plasmodium berghei. We show that four SUFs, namely SUFC, D, E, and S are refractory to targeted gene deletion, validating them as potential targets for antimalarial drug development. We achieved targeted deletion of SUFA, which encodes a potential [Fe-S] transfer protein, indicative of a dispensable role during asexual blood stage growth in vivo. Furthermore, no abnormalities were observed during Plasmodium life cycle progression in the insect and mammalian hosts. Fusion of a fluorescent tag to the endogenous P. berghei SUFs demonstrated that all loci were accessible to genetic modification and that all five tagged SUFs localize to the apicoplast. Together, our experimental genetics analysis identifies the key components of the SUF [Fe-S] cluster biosynthesis pathway in the apicoplast of a malarial parasite and shows that absence of SUFC, D, E, or S is incompatible with Plasmodium blood infection in vivo.

  11. Polypeptide release factors and stop codon recognition in the apicoplast and mitochondrion of Plasmodium falciparum.

    Science.gov (United States)

    Vaishya, Suniti; Kumar, Vikash; Gupta, Ankit; Siddiqi, Mohammad Imran; Habib, Saman

    2016-06-01

    Correct termination of protein synthesis would be a critical step in translation of organellar open reading frames (ORFs) of the apicoplast and mitochondrion of the malaria parasite. We identify release factors (RFs) responsible for recognition of the UAA and UGA stop-codons of apicoplast ORFs and the sole UAA stop-codon that terminates translation from the three mitochondrial ORFs. A single nuclear-encoded canonical RF2, PfRF2Api , localizes to the apicoplast. It has a conserved tripeptide motif (SPF) for stop-codon recognition and is sufficient for peptidyl-tRNA hydrolysis (PTH) from both UAA and UGA. Two RF family proteins are targeted to the parasite mitochondrion; a canonical RF1, PfRF1Mit , with a variant codon-recognition motif (PxN instead of the conserved RF1 PxT) is the major peptidyl-hydrolase with specific recognition of the UAA codon relevant to mitochondrial ORFs. Mutation of the N residue of the PfRF1Mit PxN motif and two other conserved residues of the codon recognition domain lowers PTH activity from pre-termination ribosomes indicating their role in codon-recognition. The second RF imported by the mitochondrion is the non-canonical PfICT1 that functions as a dimer and mediates codon nonspecific peptide release. Our results help delineate a critical step in organellar translation in Plasmodium, which is an important target for anti-malarials. PMID:26946524

  12. Apicoplast lipoic acid protein ligase B is not essential for Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Svenja Günther

    2007-12-01

    Full Text Available Lipoic acid (LA is an essential cofactor of alpha-keto acid dehydrogenase complexes (KADHs and the glycine cleavage system. In Plasmodium, LA is attached to the KADHs by organelle-specific lipoylation pathways. Biosynthesis of LA exclusively occurs in the apicoplast, comprising octanoyl-[acyl carrier protein]: protein N-octanoyltransferase (LipB and LA synthase. Salvage of LA is mitochondrial and scavenged LA is ligated to the KADHs by LA protein ligase 1 (LplA1. Both pathways are entirely independent, suggesting that both are likely to be essential for parasite survival. However, disruption of the LipB gene did not negatively affect parasite growth despite a drastic loss of LA (>90%. Surprisingly, the sole, apicoplast-located pyruvate dehydrogenase still showed lipoylation, suggesting that an alternative lipoylation pathway exists in this organelle. We provide evidence that this residual lipoylation is attributable to the dual targeted, functional lipoate protein ligase 2 (LplA2. Localisation studies show that LplA2 is present in both mitochondrion and apicoplast suggesting redundancy between the lipoic acid protein ligases in the erythrocytic stages of P. falciparum.

  13. Autophagy-related Atg8 localizes to the apicoplast of the human malaria parasite Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Kei Kitamura

    Full Text Available Autophagy is a membrane-mediated degradation process, which is governed by sequential functions of Atg proteins. Although Atg proteins are highly conserved in eukaryotes, protozoa possess only a partial set of Atg proteins. Nonetheless, almost all protozoa have the complete factors belonging to the Atg8 conjugation system, namely, Atg3, Atg4, Atg7, and Atg8. Here, we report the biochemical properties and subcellular localization of the Atg8 protein of the human malaria parasite Plasmodium falciparum (PfAtg8. PfAtg8 is expressed during intra-erythrocytic development and associates with membranes likely as a lipid-conjugated form. Fluorescence microscopy and immunoelectron microscopy show that PfAtg8 localizes to the apicoplast, a four membrane-bound non-photosynthetic plastid. Autophagosome-like structures are not observed in the erythrocytic stages. These data suggest that, although Plasmodium parasites have lost most Atg proteins during evolution, they use the Atg8 conjugation system for the unique organelle, the apicoplast.

  14. Molecular phylogeny of Toxoplasmatinae: comparison between inferences based on mitochondrial and apicoplast genetic sequences

    Directory of Open Access Journals (Sweden)

    Michelle Klein Sercundes

    2016-03-01

    Full Text Available Abstract Phylogenies within Toxoplasmatinae have been widely investigated with different molecular markers. Here, we studied molecular phylogenies of the Toxoplasmatinae subfamily based on apicoplast and mitochondrial genes. Partial sequences of apicoplast genes coding for caseinolytic protease (clpC and beta subunit of RNA polymerase (rpoB, and mitochondrial gene coding for cytochrome B (cytB were analyzed. Laboratory-adapted strains of the closely related parasites Sarcocystis falcatula and Sarcocystis neurona were investigated, along with Neospora caninum, Neospora hughesi, Toxoplasma gondii (strains RH, CTG and PTG, Besnoitia akodoni, Hammondia hammondiand two genetically divergent lineages of Hammondia heydorni. The molecular analysis based on organellar genes did not clearly differentiate between N. caninum and N. hughesi, but the two lineages of H. heydorni were confirmed. Slight differences between the strains of S. falcatula and S. neurona were encountered in all markers. In conclusion, congruent phylogenies were inferred from the three different genes and they might be used for screening undescribed sarcocystid parasites in order to ascertain their phylogenetic relationships with organisms of the family Sarcocystidae. The evolutionary studies based on organelar genes confirm that the genusHammondia is paraphyletic. The primers used for amplification of clpC and rpoB were able to amplify genetic sequences of organisms of the genus Sarcocystisand organisms of the subfamily Toxoplasmatinae as well.

  15. Molecular phylogeny of Toxoplasmatinae: comparison between inferences based on mitochondrial and apicoplast genetic sequences.

    Science.gov (United States)

    Sercundes, Michelle Klein; Valadas, Samantha Yuri Oshiro Branco; Keid, Lara Borges; Oliveira, Tricia Maria Ferreira Souza; Ferreira, Helena Lage; Vitor, Ricardo Wagner de Almeida; Gregori, Fábio; Soares, Rodrigo Martins

    2016-01-01

    Phylogenies within Toxoplasmatinae have been widely investigated with different molecular markers. Here, we studied molecular phylogenies of the Toxoplasmatinae subfamily based on apicoplast and mitochondrial genes. Partial sequences of apicoplast genes coding for caseinolytic protease (clpC) and beta subunit of RNA polymerase (rpoB), and mitochondrial gene coding for cytochrome B (cytB) were analyzed. Laboratory-adapted strains of the closely related parasites Sarcocystis falcatula and Sarcocystis neurona were investigated, along with Neospora caninum, Neospora hughesi, Toxoplasma gondii (strains RH, CTG and PTG), Besnoitia akodoni, Hammondia hammondiand two genetically divergent lineages of Hammondia heydorni. The molecular analysis based on organellar genes did not clearly differentiate between N. caninum and N. hughesi, but the two lineages of H. heydorni were confirmed. Slight differences between the strains of S. falcatula and S. neurona were encountered in all markers. In conclusion, congruent phylogenies were inferred from the three different genes and they might be used for screening undescribed sarcocystid parasites in order to ascertain their phylogenetic relationships with organisms of the family Sarcocystidae. The evolutionary studies based on organelar genes confirm that the genus Hammondia is paraphyletic. The primers used for amplification of clpC and rpoB were able to amplify genetic sequences of organisms of the genus Sarcocystisand organisms of the subfamily Toxoplasmatinae as well. PMID:27007245

  16. Crystallization and preliminary X-ray analysis of the Plasmodium falciparum apicoplast DNA polymerase.

    Science.gov (United States)

    Milton, Morgan E; Choe, Jun-yong; Honzatko, Richard B; Nelson, Scott W

    2015-03-01

    Infection by the parasite Plasmodium falciparum is the leading cause of malaria in humans. The parasite has a unique and essential plastid-like organelle called the apicoplast. The apicoplast contains a genome that undergoes replication and repair through the action of a replicative polymerase (apPOL). apPOL has no direct orthologs in mammalian polymerases and is therefore an attractive antimalarial drug target. No structural information exists for apPOL, and the Klenow fragment of Escherichia coli DNA polymerase I, which is its closest structural homolog, shares only 28% sequence identity. Here, conditions for the crystallization of and preliminary X-ray diffraction data from crystals of P. falciparum apPOL are reported. Data complete to 3.5 Å resolution were collected from a single crystal (2 × 2 × 5 µm) using a 5 µm beam. The space group P6522 (unit-cell parameters a = b = 141.8, c = 149.7 Å, α = β = 90, γ = 120°) was confirmed by molecular replacement. Refinement is in progress. PMID:25760711

  17. Plasmodium Apicoplast Gln-tRNA Gln Biosynthesis Utilizes a Unique GatAB Amidotransferase Essential for Erythrocytic Stage Parasites

    KAUST Repository

    Mailu, Boniface M.

    2015-08-28

    © 2015 by The American Society for Biochemistry and Molecular Biology, Inc. The malaria parasite Plasmodium falciparum apicoplast indirect aminoacylation pathway utilizes a non-discriminating glutamyl-tRNA synthetase to synthesize Glu-tRNAGln and a glutaminyl-tRNA amidotransferase to convert Glu-tRNAGln to Gln-tRNAGln. Here, we show that Plasmodium falciparum and other apicomplexans possess a unique heterodimeric glutamyltRNA amidotransferase consisting of GatA and GatB subunits (GatAB). We localized the P. falciparum GatA and GatB subunits to the apicoplast in blood stage parasites and demonstrated that recombinant GatAB converts Glu-tRNAGln to Gln-tRNAGln in vitro. We demonstrate that the apicoplast GatAB-catalyzed reaction is essential to the parasite blood stages because we could not delete the Plasmodium berghei gene encoding GatA in blood stage parasites in vivo. A phylogenetic analysis placed the split between Plasmodium GatB, archaeal GatE, and bacterial GatB prior to the phylogenetic divide between bacteria and archaea. Moreover, Plasmodium GatA also appears to have emerged prior to the bacterial-archaeal phylogenetic divide. Thus, although GatAB is found in Plasmodium, it emerged prior to the phylogenetic separation of archaea and bacteria.

  18. Apicoplast-Localized Lysophosphatidic Acid Precursor Assembly Is Required for Bulk Phospholipid Synthesis in Toxoplasma gondii and Relies on an Algal/Plant-Like Glycerol 3-Phosphate Acyltransferase.

    Science.gov (United States)

    Amiar, Souad; MacRae, James I; Callahan, Damien L; Dubois, David; van Dooren, Giel G; Shears, Melanie J; Cesbron-Delauw, Marie-France; Maréchal, Eric; McConville, Malcolm J; McFadden, Geoffrey I; Yamaryo-Botté, Yoshiki; Botté, Cyrille Y

    2016-08-01

    Most apicomplexan parasites possess a non-photosynthetic plastid (the apicoplast), which harbors enzymes for a number of metabolic pathways, including a prokaryotic type II fatty acid synthesis (FASII) pathway. In Toxoplasma gondii, the causative agent of toxoplasmosis, the FASII pathway is essential for parasite growth and infectivity. However, little is known about the fate of fatty acids synthesized by FASII. In this study, we have investigated the function of a plant-like glycerol 3-phosphate acyltransferase (TgATS1) that localizes to the T. gondii apicoplast. Knock-down of TgATS1 resulted in significantly reduced incorporation of FASII-synthesized fatty acids into phosphatidic acid and downstream phospholipids and a severe defect in intracellular parasite replication and survival. Lipidomic analysis demonstrated that lipid precursors are made in, and exported from, the apicoplast for de novo biosynthesis of bulk phospholipids. This study reveals that the apicoplast-located FASII and ATS1, which are primarily used to generate plastid galactolipids in plants and algae, instead generate bulk phospholipids for membrane biogenesis in T. gondii. PMID:27490259

  19. Apicoplast fatty acid synthesis is essential for pellicle formation at the end of cytokinesis in Toxoplasma gondii.

    Science.gov (United States)

    Martins-Duarte, Érica S; Carias, Maira; Vommaro, Rossiane; Surolia, Namita; de Souza, Wanderley

    2016-09-01

    The apicomplexan protozoan Toxoplasma gondii, the causative agent of toxoplasmosis, harbors an apicoplast, a plastid-like organelle with essential metabolic functions. Although the FASII fatty acid biosynthesis pathway located in the apicoplast is essential for parasite survival, the cellular effects of FASII disruption in T. gondii had not been examined in detail. Here, we combined light and electron microscopy techniques - including focused ion beam scanning electron microscopy (FIB-SEM) - to characterize the effect of FASII disruption in T. gondii, by treatment with the FASII inhibitor triclosan or by inducible knockdown of the FASII component acyl carrier protein. Morphological analyses showed that FASII disruption prevented cytokinesis completion in T. gondii tachyzoites, leading to the formation of large masses of 'tethered' daughter cells. FIB-SEM showed that tethered daughters had a mature basal complex, but a defect in new membrane addition between daughters resulted in incomplete pellicle formation. Addition of exogenous fatty acids to medium suppressed the formation of tethered daughter cells and supports the notion that FASII is essential to generate lipid substrates required for the final step of parasite division. PMID:27457282

  20. Identification of vital and dispensable sulfur utilization factors in the Plasmodium apicoplast

    NARCIS (Netherlands)

    Haussig, J.M.; Matuschewski, K.; Kooij, T.W.A.

    2014-01-01

    Iron-sulfur [Fe-S] clusters are ubiquitous and critical cofactors in diverse biochemical processes. They are assembled by distinct [Fe-S] cluster biosynthesis pathways, typically in organelles of endosymbiotic origin. Apicomplexan parasites, including Plasmodium, the causative agent of malaria, harb

  1. 质体样细胞器APICOPLAST起源的分子证据评述%Molecular Evidence for Origin of Plastid-like Organelle Apicoplast: a Review

    Institute of Scientific and Technical Information of China (English)

    朱新宇; 张瑶; 周鸣鸣

    2005-01-01

    顶复合器门的原生动物(Apicomplexan protozoa)含有一个高度退化的质体样(pIastid-like)细胞器,定名为apicoplast.Apicoplast的进化起源是一个长期激烈争论的问题,尽管使用了多种分子技术,但尚未取得一致的结论,以致成为质体起源研究的典型案例.文章评述了apicoplast起源研究的分子证据,分析了新的分子证据的可能来源,为进一步研究提供线索.

  2. Telithromycin and Quinupristin-Dalfopristin Induce Delayed Death in Plasmodium falciparum▿

    OpenAIRE

    Barthel, Diana; Schlitzer, Martin; Pradel, Gabriele

    2007-01-01

    Antibacterial agents are used in malaria therapy due to their effect on two prokaryote organelles, the mitochondrion and the apicoplast. We demonstrate here that the ribosome-blocking antibiotics telithromycin and quinupristin-dalfopristin, but not linezolid, inhibit the growth of Plasmodium falciparum. Both drugs induce delayed death in the parasite, suggesting that their effect involves the impairment of apicoplast translation processes.

  3. Localization of heme biosynthesis pathway enzymes in Plasmodium falciparum.

    Science.gov (United States)

    Rao, Aditya; Yeleswarapu, Sri Jyothsna; Srinivasan, Rajgopal; Bulusu, Gopalakrishnan

    2008-12-01

    Protein trafficking in the malarial parasite Plasmodium falciparum is dictated by a complex life-cycle that involves a variety of intra-cellular and host cell destinations, such as the mitochondrion, apicoplast, rhoptries and micronemes. Of these, the apicoplast and mitochondrion are believed to account for more than 10% of this traffic. Studies have shown that mechanisms for mitochondrion and apicoplast targeting are distinct, despite their close physical proximity. The heme biosynthesis pathway spans both these organelles, making trafficking studies crucial for the spatial demarcation of the constituent interactions. This minireview highlights the challenges in identifying the possible sub-cellular destinations of the heme pathway enzymes using gleanings from literature survey as well as focussed bioinformatic analysis. PMID:19239121

  4. Ciprofloxacin Derivatives Affect Parasite Cell Division and Increase the Survival of Mice Infected with Toxoplasma gondii.

    Directory of Open Access Journals (Sweden)

    Erica S Martins-Duarte

    Full Text Available Toxoplasmosis, caused by the protozoan Toxoplasma gondii, is a worldwide disease whose clinical manifestations include encephalitis and congenital malformations in newborns. Previously, we described the synthesis of new ethyl-ester derivatives of the antibiotic ciprofloxacin with ~40-fold increased activity against T. gondii in vitro, compared with the original compound. Cipro derivatives are expected to target the parasite's DNA gyrase complex in the apicoplast. The activity of these compounds in vivo, as well as their mode of action, remained thus far uncharacterized. Here, we examined the activity of the Cipro derivatives in vivo, in a model of acute murine toxoplasmosis. In addition, we investigated the cellular effects T. gondii tachyzoites in vitro, by immunofluorescence and transmission electron microscopy (TEM. When compared with Cipro treatment, 7-day treatments with Cipro derivatives increased mouse survival significantly, with 13-25% of mice surviving for up to 60 days post-infection (vs. complete lethality 10 days post-infection, with Cipro treatment. Light microscopy examination early (6 and 24h post-infection revealed that 6-h treatments with Cipro derivatives inhibited the initial event of parasite cell division inside host cells, in an irreversible manner. By TEM and immunofluorescence, the main cellular effects observed after treatment with Cipro derivatives and Cipro were cell scission inhibition--with the appearance of 'tethered' parasites--malformation of the inner membrane complex, and apicoplast enlargement and missegregation. Interestingly, tethered daughter cells resulting from Cipro derivatives, and also Cipro, treatment did not show MORN1 cap or centrocone localization. The biological activity of Cipro derivatives against C. parvum, an apicomplexan species that lacks the apicoplast, is, approximately, 50 fold lower than that in T. gondii tachyzoites, supporting that these compounds targets the apicoplast. Our results

  5. The multifunctional autophagy pathway in the human malaria parasite, Plasmodium falciparum

    Science.gov (United States)

    Cervantes, Serena; Bunnik, Evelien M; Saraf, Anita; Conner, Christopher M; Escalante, Aster; Sardiu, Mihaela E; Ponts, Nadia; Prudhomme, Jacques; Florens, Laurence; Le Roch, Karine G

    2014-01-01

    Autophagy is a catabolic pathway typically induced by nutrient starvation to recycle amino acids, but can also function in removing damaged organelles. In addition, this pathway plays a key role in eukaryotic development. To date, not much is known about the role of autophagy in apicomplexan parasites and more specifically in the human malaria parasite Plasmodium falciparum. Comparative genomic analysis has uncovered some, but not all, orthologs of autophagy-related (ATG) genes in the malaria parasite genome. Here, using a genome-wide in silico analysis, we confirmed that ATG genes whose products are required for vesicle expansion and completion are present, while genes involved in induction of autophagy and cargo packaging are mostly absent. We subsequently focused on the molecular and cellular function of P. falciparum ATG8 (PfATG8), an autophagosome membrane marker and key component of the autophagy pathway, throughout the parasite asexual and sexual erythrocytic stages. In this context, we showed that PfATG8 has a distinct and atypical role in parasite development. PfATG8 localized in the apicoplast and in vesicles throughout the cytosol during parasite development. Immunofluorescence assays of PfATG8 in apicoplast-minus parasites suggest that PfATG8 is involved in apicoplast biogenesis. Furthermore, treatment of parasite cultures with bafilomycin A1 and chloroquine, both lysosomotropic agents that inhibit autophagosome and lysosome fusion, resulted in dramatic morphological changes of the apicoplast, and parasite death. Furthermore, deep proteomic analysis of components associated with PfATG8 indicated that it may possibly be involved in ribophagy and piecemeal microautophagy of the nucleus. Collectively, our data revealed the importance and specificity of the autophagy pathway in the malaria parasite and offer potential novel therapeutic strategies. PMID:24275162

  6. Role of Different Pfcrt and Pfmdr-1 Mutations in Conferring Resistance to Antimalaria Drugs in Plasmodium falciparum

    OpenAIRE

    Zaid O. Ibraheem; Abd Majid, R.; S. Mohd Noor; H. Mohd. Sedik; Basir, R.

    2014-01-01

    Emergence of drugs resistant strains of Plasmodium falciparum has augmented the scourge of malaria in endemic areas. Antimalaria drugs act on different intracellular targets. The majority of them interfere with digestive vacuoles (DVs) while others affect other organelles, namely, apicoplast and mitochondria. Prevention of drug accumulation or access into the target site is one of the mechanisms that plasmodium adopts to develop resistance. Plasmodia are endowed with series of transporters th...

  7. Structural and functional characterization of an iron-sulfur cluster assembly scaffold protein-SufA from Plasmodium vivax.

    Science.gov (United States)

    Pala, Zarna Rajeshkumar; Saxena, Vishal; Saggu, Gagandeep Singh; Yadav, Sushil Kumar; Pareek, R P; Kochar, Sanjay Kumar; Kochar, Dhanpat Kumar; Garg, Shilpi

    2016-07-01

    Iron-sulfur (Fe-S) clusters are utilized as prosthetic groups in all living organisms for diverse range of cellular processes including electron transport in respiration and photosynthesis, sensing of ambient conditions, regulation of gene expression and catalysis. In Plasmodium, two Fe-S cluster biogenesis pathways are reported, of which the Suf pathway in the apicoplast has been shown essential for the erythrocytic stages of the parasite. While the initial components of this pathway detailing the sulfur mobilization have been elucidated, the components required for the assembly and transfer of Fe-S clusters are not reported from the parasite. In Escherichia coli, SufB acts as a scaffold protein and SufA traffics the assembled Fe-S cluster from SufB to target apo-proteins. However, in Plasmodium, the homologs of these proteins are yet to be characterized for their function. Here, we report a putative SufA protein from Plasmodium vivax with signature motifs of A-type scaffold proteins, which is evolutionarily conserved. The presence of the [Fe4S4](3+) cluster under reduced conditions was confirmed by UV-visible and EPR spectroscopy and the interaction of these clusters with the conserved cysteine residues of chains A and B of PvSufA, validates its existence as a dimer, similar to that in E. coli. The H-bond interactions at the PvSufA-SufB interface demonstrate SufA as a scaffold protein in conjunction with SufB for the pre-assembly of Fe-S clusters and their transfer to the target proteins. Co-localization of the protein to the apicoplast further provides an experimental evidence of a functional scaffold protein SufA for the biogenesis of Fe-S clusters in apicoplast of Plasmodium. PMID:27033210

  8. DNA topoisomerases in apicomplexan parasites: promising targets for drug discovery.

    Science.gov (United States)

    García-Estrada, Carlos; Prada, Christopher Fernández; Fernández-Rubio, Celia; Rojo-Vázquez, Francisco; Balaña-Fouce, Rafael

    2010-06-22

    The phylum Apicomplexa includes a large group of protozoan parasites responsible for a wide range of animal and human diseases. Destructive pathogens, such as Plasmodium falciparum and Plasmodium vivax, causative agents of human malaria, Cryptosporidium parvum, responsible of childhood diarrhoea, and Toxoplasma gondii, responsible for miscarriages and abortions in humans, are frequently associated with HIV immunosuppression in AIDS patients. The lack of effective vaccines, along with years of increasing pressure to eradicate outbreaks with the use of drugs, has favoured the formation of multi-drug resistant strains in endemic areas. Almost all apicomplexan of medical interest contain two endosymbiotic organelles that contain their own mitochondrial and apicoplast DNA. Apicoplast is an attractive target for drug testing because in addition to harbouring singular metabolic pathways absent in the host, it also has its own transcription and translation machinery of bacterial origin. Accordingly, apicomplexan protozoa contain an interesting mixture of enzymes to unwind DNA from eukaryotic and prokaryotic origins. On the one hand, the main mechanism of DNA unwinding includes the scission of one-type I-or both DNA strands-type II eukaryotic topoisomerases, establishing transient covalent bonds with the scissile end. These enzymes are targeted by camptothecin and etoposide, respectively, two natural drugs whose semisynthetic derivatives are currently used in cancer chemotherapy. On the other hand, DNA gyrase is a bacterial-borne type II DNA topoisomerase that operates within the apicoplast and is effectively targeted by bacterial antibiotics like fluoroquinolones and aminocoumarins. The present review is an update on the new findings concerning topoisomerases in apicomplexan parasites and the role of these enzymes as targets for therapeutic agents. PMID:20200034

  9. Characterization of the autophagy marker protein Atg8 reveals atypical features of autophagy in Plasmodium falciparum.

    Directory of Open Access Journals (Sweden)

    Rahul Navale

    Full Text Available Conventional autophagy is a lysosome-dependent degradation process that has crucial homeostatic and regulatory functions in eukaryotic organisms. As malaria parasites must dispose a number of self and host cellular contents, we investigated if autophagy in malaria parasites is similar to the conventional autophagy. Genome wide analysis revealed a partial autophagy repertoire in Plasmodium, as homologs for only 15 of the 33 yeast autophagy proteins could be identified, including the autophagy marker Atg8. To gain insights into autophagy in malaria parasites, we investigated Plasmodium falciparum Atg8 (PfAtg8 employing techniques and conditions that are routinely used to study autophagy. Atg8 was similarly expressed and showed punctate localization throughout the parasite in both asexual and sexual stages; it was exclusively found in the pellet fraction as an integral membrane protein, which is in contrast to the yeast or mammalian Atg8 that is distributed among cytosolic and membrane fractions, and suggests for a constitutive autophagy. Starvation, the best known autophagy inducer, decreased PfAtg8 level by almost 3-fold compared to the normally growing parasites. Neither the Atg8-associated puncta nor the Atg8 expression level was significantly altered by treatment of parasites with routinely used autophagy inhibitors (cysteine (E64 and aspartic (pepstatin protease inhibitors, the kinase inhibitor 3-methyladenine, and the lysosomotropic agent chloroquine, indicating an atypical feature of autophagy. Furthermore, prolonged inhibition of the major food vacuole protease activity by E64 and pepstatin did not cause accumulation of the Atg8-associated puncta in the food vacuole, suggesting that autophagy is primarily not meant for degradative function in malaria parasites. Atg8 showed partial colocalization with the apicoplast; doxycycline treatment, which disrupts apicoplast, did not affect Atg8 localization, suggesting a role, but not exclusive, in

  10. A first glimpse into the pattern and scale of gene transfer in the Apicomplexa

    DEFF Research Database (Denmark)

    Huang, J.L.; Mullapudi, N.; Sicheritz-Pontén, Thomas; Kissinger, J.C.

    2004-01-01

    Reports of plant-like and bacterial-like genes for a number of parasitic organisms, most notably those within the Apicomplexa and Kinetoplastida, have appeared in the literature over the last few years. Among the apicomplexan organisms, following discovery of the apicomplexan plastid (apicoplast...... combined with a phylogenomic approach to detect potential gene transfers in four apicomplexan genomes. We have detected genes of algal nuclear, chloroplast (cyanobacterial) and proteobacterial origin. Plant-like genes were detected in species not currently harbouring a plastid (e.g. Cryptosporidium parvum...

  11. Dicty_cDB: Contig-U01876-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available d Phytophthora infe... 36 9.6 3 ( EF640401 ) Libellula saturata 12S ri...mena thermophila strain SB210 mitochondrio... 36 0.45 9 ( AY217738 ) Eimeria tenella apicoplast, compl... 0.66 20 ( AM443874 ) Vitis vinifera contig VV78X089951.4, whole genome... 44 0.69 2 ( CP000049 ) Borrelia turicatae 91E135, compl... 1.2 2 ( CU633648 ) Pig DNA sequence *** SEQUENCING IN PROGRESS *** f... 46 1.3 5 ( CP000770 ) Candidatus Sulcia muelleri...ium discoideum chromosome 2 map 4158743... 32 2.3 6 ( DQ158857 ) Bigelowiell

  12. Dicty_cDB: Contig-U04589-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available 4 1 ( BX950229 ) Methanococcus maripaludis strain S2, complete seq... 44 6.4 1 ( AE013218 ) Buchnera aphidicola str. Sg (Schizap...ped Lambda K H 1.37 0.711 1.31 Matrix: blastn matrix:1 -3 Gap Penalties: Existence: 5, Extension: 2 Number ...AX345418 ) Sequence 489 from Patent WO0200928. 44 0.41 2 ( CU695284 ) Brassica rapa...5 ( X95275 ) Plasmodium falciparum complete gene map of plastid-... 34 2.2 4 ( AC208877 ) Homo sapiens FOSMI...a crassa DNA linkage group II BAC contig... 34 3.3 2 ( DQ642846 ) Plasmodium falciparum HB3 apicoplast, comp

  13. Endosymbiosis undone by stepwise elimination of the plastid in a parasitic dinoflagellate

    KAUST Repository

    Gornik, Sebastian G.

    2015-04-20

    Organelle gain through endosymbiosis has been integral to the origin and diversification of eukaryotes, and, once gained, plastids and mitochondria seem seldom lost. Indeed, discovery of nonphotosynthetic plastids in many eukaryotes - notably, the apicoplast in apicomplexan parasites such as the malaria pathogen Plasmodium - highlights the essential metabolic functions performed by plastids beyond photosynthesis. Once a cell becomes reliant on these ancillary functions, organelle dependence is apparently difficult to overcome. Previous examples of endosymbiotic organelle loss (either mitochondria or plastids), which have been invoked to explain the origin of eukaryotic diversity, have subsequently been recognized as organelle reduction to cryptic forms, such as mitosomes and apicoplasts. Integration of these ancient symbionts with their hosts has been too well developed to reverse. Here, we provide evidence that the dinoflagellate Hematodinium sp., a marine parasite of crustaceans, represents a rare case of endosymbiotic organelle loss by the elimination of the plastid. Extensive RNA and genomic sequencing data provide no evidence for a plastid organelle, but, rather, reveal a metabolic decoupling from known plastid functions that typically impede organelle loss. This independence has been achieved through retention of ancestral anabolic pathways, enzyme relocation from the plastid to the cytosol, and metabolic scavenging from the parasite\\'s host. Hematodinium sp. thus represents a further dimension of endosymbiosis-life after the organelle. © 2015, National Academy of Sciences. All rights reserved.

  14. The Clp Chaperones and Proteases of the Human Malaria Parasite Plasmodium falciparum

    Energy Technology Data Exchange (ETDEWEB)

    M El Bakkouri; A Pow; A Mulichak; K Cheung; J Artz; M Amani; S Fell; T de Koning-Ward; C Goodman; et al.

    2011-12-31

    The Clpchaperones and proteases play an important role in protein homeostasis in the cell. They are highly conserved across prokaryotes and found also in the mitochondria of eukaryotes and the chloroplasts of plants. They function mainly in the disaggregation, unfolding and degradation of native as well as misfolded proteins. Here, we provide a comprehensive analysis of the Clpchaperones and proteases in the humanmalariaparasitePlasmodiumfalciparum. The parasite contains four Clp ATPases, which we term PfClpB1, PfClpB2, PfClpC and PfClpM. One PfClpP, the proteolytic subunit, and one PfClpR, which is an inactive version of the protease, were also identified. Expression of all Clpchaperones and proteases was confirmed in blood-stage parasites. The proteins were localized to the apicoplast, a non-photosynthetic organelle that accommodates several important metabolic pathways in P. falciparum, with the exception of PfClpB2 (also known as Hsp101), which was found in the parasitophorous vacuole. Both PfClpP and PfClpR form mostly homoheptameric rings as observed by size-exclusion chromatography, analytical ultracentrifugation and electron microscopy. The X-ray structure of PfClpP showed the protein as a compacted tetradecamer similar to that observed for Streptococcus pneumoniae and Mycobacterium tuberculosis ClpPs. Our data suggest the presence of a ClpCRP complex in the apicoplast of P. falciparum.

  15. Two recently sequenced vertebrate genomes are contaminated with apicomplexan species of the Sarcocystidae family.

    Science.gov (United States)

    Orosz, Ferenc

    2015-11-01

    This paper highlights a general problem, namely that host genome sequences can easily be contaminated with parasite sequences, thus careful isolation of genetic material and careful bioinformatics analysis are needed in all cases. Two recently published genomes are shown here to be contaminated with sequences of apicomplexan parasites which belong to the Sarcocystidae family. Sequences of the characteristic apicomplexan organelle, the apicoplast, were used as queries in BLASTN searches against nucleotide sequences of various animal groups looking for possible contamination. Draft genomes of a bird, Colinus virginianus (Halley et al., 2014), and a bat, Myotis davidii (Zhang et al., 2013) were found to contain at least six and 17 contigs, respectively, originating from the apicoplast of an apicomplexan species, and other genes specific to this phylum can also be found in the published genomes. Obviously, the sources of the genetic material, the muscle and the kidney of the animals, respectively, contained the parasitic cysts. Phylogenetic analyses using 18S rRNA and internal transcribed spacer 1 genes show that the parasite contaminating C. virginianus is a species of Sarcocystis related to ones known to cycle between avian and mammalian hosts. In the case of M. davidii it belongs to the Nephroisospora genus, the only member of which, Nephroisospora eptesici, has been recently identified from the kidney of big brown bats (Eptesicus fuscus). PMID:26264549

  16. The Clp Chaperones and Proteases of the Human Malaria Parasite Plasmodium falciparum

    Energy Technology Data Exchange (ETDEWEB)

    Bakkouri, Majida El; Pow, Andre; Mulichak, Anne; Cheung, Kevin L.Y.; Artz, Jennifer D.; Amani, Mehrnaz; Fell, Stuart; de Koning-Ward, Tania F.; Goodman, C. Dean; McFadden, Geoffrey I.; Ortega, Joaquin; Hui, Raymond; Houry, Walid A. (McMaster U.); (Melbourne); (Toronto); (Deakin); (HWMRI)

    2015-02-09

    The Clp chaperones and proteases play an important role in protein homeostasis in the cell. They are highly conserved across prokaryotes and found also in the mitochondria of eukaryotes and the chloroplasts of plants. They function mainly in the disaggregation, unfolding and degradation of native as well as misfolded proteins. Here, we provide a comprehensive analysis of the Clp chaperones and proteases in the human malaria parasite Plasmodium falciparum. The parasite contains four Clp ATPases, which we term PfClpB1, PfClpB2, PfClpC and PfClpM. One PfClpP, the proteolytic subunit, and one PfClpR, which is an inactive version of the protease, were also identified. Expression of all Clp chaperones and proteases was confirmed in blood-stage parasites. The proteins were localized to the apicoplast, a non-photosynthetic organelle that accommodates several important metabolic pathways in P. falciparum, with the exception of PfClpB2 (also known as Hsp101), which was found in the parasitophorous vacuole. Both PfClpP and PfClpR form mostly homoheptameric rings as observed by size-exclusion chromatography, analytical ultracentrifugation and electron microscopy. The X-ray structure of PfClpP showed the protein as a compacted tetradecamer similar to that observed for Streptococcus pneumoniae and Mycobacterium tuberculosis ClpPs. Our data suggest the presence of a ClpCRP complex in the apicoplast of P. falciparum.

  17. Regulation of Expression and Evolution of Genes in Plastids of Rhodophytic Branch.

    Science.gov (United States)

    Zverkov, Oleg Anatolyevich; Seliverstov, Alexandr Vladislavovich; Lyubetsky, Vassily Alexandrovich

    2016-01-01

    A novel algorithm and original software were used to cluster all proteins encoded in plastids of 72 species of the rhodophytic branch. The results are publicly available at http://lab6.iitp.ru/ppc/redline72/ in a database that allows fast identification of clusters (protein families) both by a fragment of an amino acid sequence and by a phylogenetic profile of a protein. No such integral clustering with the corresponding functions can be found in the public domain. The putative regulons of the transcription factors Ycf28 and Ycf29 encoded in the plastids were identified using the clustering and the database. A regulation of translation initiation was proposed for the ycf24 gene in plastids of certain red algae and apicomplexans as well as a regulation of a putative gene in apicoplasts of Babesia spp. and Theileria parva. The conserved regulation of the ycf24 gene expression and specificity alternation of the transcription factor Ycf28 were shown in the plastids. A phylogenetic tree of plastids was generated for the rhodophytic branch. The hypothesis of the origin of apicoplasts from the common ancestor of all apicomplexans from plastids of red algae was confirmed. PMID:26840333

  18. Regulation of Expression and Evolution of Genes in Plastids of Rhodophytic Branch

    Science.gov (United States)

    Zverkov, Oleg Anatolyevich; Seliverstov, Alexandr Vladislavovich; Lyubetsky, Vassily Alexandrovich

    2016-01-01

    A novel algorithm and original software were used to cluster all proteins encoded in plastids of 72 species of the rhodophytic branch. The results are publicly available at http://lab6.iitp.ru/ppc/redline72/ in a database that allows fast identification of clusters (protein families) both by a fragment of an amino acid sequence and by a phylogenetic profile of a protein. No such integral clustering with the corresponding functions can be found in the public domain. The putative regulons of the transcription factors Ycf28 and Ycf29 encoded in the plastids were identified using the clustering and the database. A regulation of translation initiation was proposed for the ycf24 gene in plastids of certain red algae and apicomplexans as well as a regulation of a putative gene in apicoplasts of Babesia spp. and Theileria parva. The conserved regulation of the ycf24 gene expression and specificity alternation of the transcription factor Ycf28 were shown in the plastids. A phylogenetic tree of plastids was generated for the rhodophytic branch. The hypothesis of the origin of apicoplasts from the common ancestor of all apicomplexans from plastids of red algae was confirmed. PMID:26840333

  19. A barcode of organellar genome polymorphisms identifies the geographic origin of Plasmodium falciparum strains

    KAUST Repository

    Preston, Mark D.

    2014-06-13

    Malaria is a major public health problem that is actively being addressed in a global eradication campaign. Increased population mobility through international air travel has elevated the risk of re-introducing parasites to elimination areas and dispersing drug-resistant parasites to new regions. A simple genetic marker that quickly and accurately identifies the geographic origin of infections would be a valuable public health tool for locating the source of imported outbreaks. Here we analyse the mitochondrion and apicoplast genomes of 711 Plasmodium falciparum isolates from 14 countries, and find evidence that they are non-recombining and co-inherited. The high degree of linkage produces a panel of relatively few single-nucleotide polymorphisms (SNPs) that is geographically informative. We design a 23-SNP barcode that is highly predictive (?92%) and easily adapted to aid case management in the field and survey parasite migration worldwide. 2014 Macmillan Publishers Limited. All rights reserved.

  20. Plasmodium falciparum: multifaceted resistance to artemisinins.

    Science.gov (United States)

    Paloque, Lucie; Ramadani, Arba P; Mercereau-Puijalon, Odile; Augereau, Jean-Michel; Benoit-Vical, Françoise

    2016-01-01

    Plasmodium falciparum resistance to artemisinins, the most potent and fastest acting anti-malarials, threatens malaria elimination strategies. Artemisinin resistance is due to mutation of the PfK13 propeller domain and involves an unconventional mechanism based on a quiescence state leading to parasite recrudescence as soon as drug pressure is removed. The enhanced P. falciparum quiescence capacity of artemisinin-resistant parasites results from an increased ability to manage oxidative damage and an altered cell cycle gene regulation within a complex network involving the unfolded protein response, the PI3K/PI3P/AKT pathway, the PfPK4/eIF2α cascade and yet unidentified transcription factor(s), with minimal energetic requirements and fatty acid metabolism maintained in the mitochondrion and apicoplast. The detailed study of these mechanisms offers a way forward for identifying future intervention targets to fend off established artemisinin resistance. PMID:26955948

  1. A barcode of organellar genome polymorphisms identifies the geographic origin of Plasmodium falciparum strains

    Science.gov (United States)

    Preston, Mark D.; Campino, Susana; Assefa, Samuel A.; Echeverry, Diego F.; Ocholla, Harold; Amambua-Ngwa, Alfred; Stewart, Lindsay B.; Conway, David J.; Borrmann, Steffen; Michon, Pascal; Zongo, Issaka; Ouédraogo, Jean-Bosco; Djimde, Abdoulaye A.; Doumbo, Ogobara K.; Nosten, Francois; Pain, Arnab; Bousema, Teun; Drakeley, Chris J.; Fairhurst, Rick M.; Sutherland, Colin J.; Roper, Cally; Clark, Taane G.

    2014-01-01

    Malaria is a major public health problem that is actively being addressed in a global eradication campaign. Increased population mobility through international air travel has elevated the risk of re-introducing parasites to elimination areas and dispersing drug-resistant parasites to new regions. A simple genetic marker that quickly and accurately identifies the geographic origin of infections would be a valuable public health tool for locating the source of imported outbreaks. Here we analyse the mitochondrion and apicoplast genomes of 711 Plasmodium falciparum isolates from 14 countries, and find evidence that they are non-recombining and co-inherited. The high degree of linkage produces a panel of relatively few single-nucleotide polymorphisms (SNPs) that is geographically informative. We design a 23-SNP barcode that is highly predictive (~92%) and easily adapted to aid case management in the field and survey parasite migration worldwide. PMID:24923250

  2. P. falciparum cpn20 is a bona fide co-chaperonin that can replace GroES in E. coli.

    Directory of Open Access Journals (Sweden)

    Anna Vitlin Gruber

    Full Text Available Human malaria is among the most ubiquitous and destructive tropical, parasitic diseases in the world today. The causative agent, Plasmodium falciparum, contains an unusual, essential organelle known as the apicoplast. Inhibition of this degenerate chloroplast results in second generation death of the parasite and is the mechanism by which antibiotics function in treating malaria. In order to better understand the biochemistry of this organelle, we have cloned a putative, 20 kDa, co-chaperonin protein, Pf-cpn20, which localizes to the apicoplast. Although this protein is homologous to the cpn20 that is found in plant chloroplasts, its ability to function as a co-chaperonin was questioned in the past. In the present study, we carried out a structural analysis of Pf-cpn20 using circular dichroism and analytical ultracentrifugation and then used two different approaches to investigate the ability of this protein to function as a co-chaperonin. In the first approach, we purified recombinant Pf-cpn20 and tested its ability to act as a co-chaperonin for GroEL in vitro, while in the second, we examined the ability of Pf-cpn20 to complement an E. coli depletion of the essential bacterial co-chaperonin GroES. Our results demonstrate that Pf-cpn20 is fully functional as a co-chaperonin in vitro. Moreover, the parasitic co-chaperonin is able to replace GroES in E. coli at both normal and heat-shock temperatures. Thus, Pf-cpn20 functions as a co-chaperonin in chaperonin-mediated protein folding. The ability of the malarial protein to function in E. coli suggests that this simple system can be used as a tool for further analyses of Pf-cpn20 and perhaps other chaperone proteins from P. falciparum.

  3. P. falciparum cpn20 is a bona fide co-chaperonin that can replace GroES in E. coli.

    Science.gov (United States)

    Vitlin Gruber, Anna; Nisemblat, Shahar; Zizelski, Gal; Parnas, Avital; Dzikowski, Ron; Azem, Abdussalam; Weiss, Celeste

    2013-01-01

    Human malaria is among the most ubiquitous and destructive tropical, parasitic diseases in the world today. The causative agent, Plasmodium falciparum, contains an unusual, essential organelle known as the apicoplast. Inhibition of this degenerate chloroplast results in second generation death of the parasite and is the mechanism by which antibiotics function in treating malaria. In order to better understand the biochemistry of this organelle, we have cloned a putative, 20 kDa, co-chaperonin protein, Pf-cpn20, which localizes to the apicoplast. Although this protein is homologous to the cpn20 that is found in plant chloroplasts, its ability to function as a co-chaperonin was questioned in the past. In the present study, we carried out a structural analysis of Pf-cpn20 using circular dichroism and analytical ultracentrifugation and then used two different approaches to investigate the ability of this protein to function as a co-chaperonin. In the first approach, we purified recombinant Pf-cpn20 and tested its ability to act as a co-chaperonin for GroEL in vitro, while in the second, we examined the ability of Pf-cpn20 to complement an E. coli depletion of the essential bacterial co-chaperonin GroES. Our results demonstrate that Pf-cpn20 is fully functional as a co-chaperonin in vitro. Moreover, the parasitic co-chaperonin is able to replace GroES in E. coli at both normal and heat-shock temperatures. Thus, Pf-cpn20 functions as a co-chaperonin in chaperonin-mediated protein folding. The ability of the malarial protein to function in E. coli suggests that this simple system can be used as a tool for further analyses of Pf-cpn20 and perhaps other chaperone proteins from P. falciparum. PMID:23326533

  4. Targeting the gyrase of Plasmodium falciparum with topoisomerase poisons.

    Science.gov (United States)

    Tang Girdwood, Sonya C; Nenortas, Elizabeth; Shapiro, Theresa A

    2015-06-15

    Drug-resistant malaria poses a major public health problem throughout the world and the need for new antimalarial drugs is growing. The apicoplast, a chloroplast-like organelle essential for malaria parasite survival and with no counterpart in humans, offers an attractive target for selectively toxic new therapies. The apicoplast genome (plDNA) is a 35 kb circular DNA that is served by gyrase, a prokaryotic type II topoisomerase. Gyrase is poisoned by fluoroquinolone antibacterials that stabilize a catalytically inert ternary complex of enzyme, its plDNA substrate, and inhibitor. We used fluoroquinolones to study the gyrase and plDNA of Plasmodium falciparum. New methods for isolating and separating plDNA reveal four topologically different forms and permit a quantitative exam of perturbations that result from gyrase poisoning. In keeping with its role in DNA replication, gyrase is most abundant in late stages of the parasite lifecycle, but several lines of evidence indicate that even in these cells the enzyme is present in relatively low abundance: about 1 enzyme for every two plDNAs or a ratio of 1 gyrase: 70 kb DNA. For a spectrum of quinolones, correlation was generally good between antimalarial activity and gyrase poisoning, the putative molecular mechanism of drug action. However, in P. falciparum there is evidence for off-target toxicity, particularly for ciprofloxacin. These studies highlight the utility of the new methods and of fluoroquinolones as a tool for studying the in situ workings of gyrase and its plDNA substrate. PMID:25881748

  5. Knockout studies reveal an important role of Plasmodium lipoic acid protein ligase A1 for asexual blood stage parasite survival.

    Directory of Open Access Journals (Sweden)

    Svenja Günther

    Full Text Available Lipoic acid (LA is a dithiol-containing cofactor that is essential for the function of alpha-keto acid dehydrogenase complexes. LA acts as a reversible acyl group acceptor and 'swinging arm' during acyl-coenzyme A formation. The cofactor is post-translationally attached to the acyl-transferase subunits of the multienzyme complexes through the action of octanoyl (lipoyl: N-octanoyl (lipoyl transferase (LipB or lipoic acid protein ligases (LplA. Remarkably, apicomplexan parasites possess LA biosynthesis as well as scavenging pathways and the two pathways are distributed between mitochondrion and a vestigial organelle, the apicoplast. The apicoplast-specific LipB is dispensable for parasite growth due to functional redundancy of the parasite's lipoic acid/octanoic acid ligases/transferases. In this study, we show that LplA1 plays a pivotal role during the development of the erythrocytic stages of the malaria parasite. Gene disruptions in the human malaria parasite P. falciparum consistently were unsuccessful while in the rodent malaria model parasite P. berghei the LplA1 gene locus was targeted by knock-in and knockout constructs. However, the LplA1((- mutant could not be cloned suggesting a critical role of LplA1 for asexual parasite growth in vitro and in vivo. These experimental genetics data suggest that lipoylation during expansion in red blood cells largely occurs through salvage from the host erythrocytes and subsequent ligation of LA to the target proteins of the malaria parasite.

  6. The Complete Mitochondrial Genome of the Foodborne Parasitic Pathogen Cyclospora cayetanensis.

    Directory of Open Access Journals (Sweden)

    Hediye Nese Cinar

    Full Text Available Cyclospora cayetanensis is a human-specific coccidian parasite responsible for several food and water-related outbreaks around the world, including the most recent ones involving over 900 persons in 2013 and 2014 outbreaks in the USA. Multicopy organellar DNA such as mitochondrion genomes have been particularly informative for detection and genetic traceback analysis in other parasites. We sequenced the C. cayetanensis genomic DNA obtained from stool samples from patients infected with Cyclospora in Nepal using the Illumina MiSeq platform. By bioinformatically filtering out the metagenomic reads of non-coccidian origin sequences and concentrating the reads by targeted alignment, we were able to obtain contigs containing Eimeria-like mitochondrial, apicoplastic and some chromosomal genomic fragments. A mitochondrial genomic sequence was assembled and confirmed by cloning and sequencing targeted PCR products amplified from Cyclospora DNA using primers based on our draft assembly sequence. The results show that the C. cayetanensis mitochondrion genome is 6274 bp in length, with 33% GC content, and likely exists in concatemeric arrays as in Eimeria mitochondrial genomes. Phylogenetic analysis of the C. cayetanensis mitochondrial genome places this organism in a tight cluster with Eimeria species. The mitochondrial genome of C. cayetanensis contains three protein coding genes, cytochrome (cytb, cytochrome C oxidase subunit 1 (cox1, and cytochrome C oxidase subunit 3 (cox3, in addition to 14 large subunit (LSU and nine small subunit (SSU fragmented rRNA genes.

  7. Role of Different Pfcrt and Pfmdr-1 Mutations in Conferring Resistance to Antimalaria Drugs in Plasmodium falciparum.

    Science.gov (United States)

    Ibraheem, Zaid O; Abd Majid, R; Noor, S Mohd; Sedik, H Mohd; Basir, R

    2014-01-01

    Emergence of drugs resistant strains of Plasmodium falciparum has augmented the scourge of malaria in endemic areas. Antimalaria drugs act on different intracellular targets. The majority of them interfere with digestive vacuoles (DVs) while others affect other organelles, namely, apicoplast and mitochondria. Prevention of drug accumulation or access into the target site is one of the mechanisms that plasmodium adopts to develop resistance. Plasmodia are endowed with series of transporters that shuffle drugs away from the target site, namely, pfmdr (Plasmodium falciparum multidrug resistance transporter) and pfcrt (Plasmodium falciparum chloroquine resistance transporter) which exist in DV membrane and are considered as putative markers of CQ resistance. They are homologues to human P-glycoproteins (P-gh or multidrug resistance system) and members of drug metabolite transporter (DMT) family, respectively. The former mediates drifting of xenobiotics towards the DV while the latter chucks them outside. Resistance to drugs whose target site of action is intravacuolar develops when the transporters expel them outside the DVs and vice versa for those whose target is extravacuolar. In this review, we are going to summarize the possible pfcrt and pfmdr mutation and their role in changing plasmodium sensitivity to different anti-Plasmodium drugs. PMID:25506039

  8. Multigenomic Delineation of Plasmodium Species of the Laverania Subgenus Infecting Wild-Living Chimpanzees and Gorillas.

    Science.gov (United States)

    Liu, Weimin; Sundararaman, Sesh A; Loy, Dorothy E; Learn, Gerald H; Li, Yingying; Plenderleith, Lindsey J; Ndjango, Jean-Bosco N; Speede, Sheri; Atencia, Rebeca; Cox, Debby; Shaw, George M; Ayouba, Ahidjo; Peeters, Martine; Rayner, Julian C; Hahn, Beatrice H; Sharp, Paul M

    2016-01-01

    Plasmodium falciparum, the major cause of malaria morbidity and mortality worldwide, is only distantly related to other human malaria parasites and has thus been placed in a separate subgenus, termed Laverania Parasites morphologically similar to P. falciparum have been identified in African apes, but only one other Laverania species, Plasmodium reichenowi from chimpanzees, has been formally described. Although recent studies have pointed to the existence of additional Laverania species, their precise number and host associations remain uncertain, primarily because of limited sampling and a paucity of parasite sequences other than from mitochondrial DNA. To address this, we used limiting dilution polymerase chain reaction to amplify additional parasite sequences from a large number of chimpanzee and gorilla blood and fecal samples collected at two sanctuaries and 30 field sites across equatorial Africa. Phylogenetic analyses of more than 2,000 new sequences derived from the mitochondrial, nuclear, and apicoplast genomes revealed six divergent and well-supported clades within the Laverania parasite group. Although two of these clades exhibited deep subdivisions in phylogenies estimated from organelle gene sequences, these sublineages were geographically defined and not present in trees from four unlinked nuclear loci. This greatly expanded sequence data set thus confirms six, and not seven or more, ape Laverania species, of which P. reichenowi, Plasmodium gaboni, and Plasmodium billcollinsi only infect chimpanzees, whereas Plasmodium praefalciparum, Plasmodium adleri, and Pladmodium blacklocki only infect gorillas. The new sequence data also confirm the P. praefalciparum origin of human P. falciparum. PMID:27289102

  9. Molecular characterisation of three avian haemoproteids (Haemosporida, Haemoproteidae), with the description of Haemoproteus (Parahaemoproteus) palloris n. sp.

    Science.gov (United States)

    Dimitrov, Dimitar; Iezhova, Tatjana A; Zehtindjiev, Pavel; Bobeva, Aneliya; Ilieva, Mihaela; Kirilova, Miroslava; Bedev, Kiril; Sjöholm, Christoffer; Valkiūnas, Gediminas

    2016-06-01

    DNA barcoding (molecular characterisation) is a useful tool for describing the taxonomy and systematics of organisms. Over 250 species of avian haemosporidian parasites have been described using morphological characters, yet molecular techniques based on polymerase chain reaction (PCR) suggest this diversity is underestimated. Moreover, molecular techniques are particularly useful for the detection of chronic infections and tissue stages of these parasites. Species delimitation is problematic among haemosporidians, and many questions about the mechanisms and patterns of speciation, host specificity and pathogenicity are still unresolved. Accumulation of additional genetic and morphological information is needed to approach these questions. Here, we combine microscopic examination with PCR-based methods to develop molecular characterisation of Haemoproteus (Parahaemoproteus) manwelli Bennett, 1978 and Haemoproteus (Parahaemoproteus) gavrilovi Valkiūnas & Iezhova, 1990, both of which parasitise the bee-eater Merops apiaster L. We also describe a new species, Haemoproteus (Parahaemoproteus) palloris n. sp., from the blood of the willow warbler Phylloscopus trochilus (L.). We performed phylogenetic analyses with a set of mitochondrial cytochrome b (cyt b) gene lineages, which have been linked to parasite morphospecies and are available in the MalAvi database. Our findings show that morphological characters, which have been traditionally used in the description of haemosporidians, exhibit phylogenetic congruence. This study contributes to a better understanding of avian haemosporidian diversity and provides new molecular markers (cyt b and apicoplast gene sequences) for the diagnostics of inadequately investigated haemosporidian infections. PMID:27220998

  10. Multigenomic Delineation of Plasmodium Species of the Laverania Subgenus Infecting Wild-Living Chimpanzees and Gorillas

    Science.gov (United States)

    Liu, Weimin; Sundararaman, Sesh A.; Loy, Dorothy E.; Learn, Gerald H.; Li, Yingying; Plenderleith, Lindsey J.; Ndjango, Jean-Bosco N.; Speede, Sheri; Atencia, Rebeca; Cox, Debby; Shaw, George M.; Ayouba, Ahidjo; Peeters, Martine; Rayner, Julian C.; Hahn, Beatrice H.; Sharp, Paul M.

    2016-01-01

    Plasmodium falciparum, the major cause of malaria morbidity and mortality worldwide, is only distantly related to other human malaria parasites and has thus been placed in a separate subgenus, termed Laverania. Parasites morphologically similar to P. falciparum have been identified in African apes, but only one other Laverania species, Plasmodium reichenowi from chimpanzees, has been formally described. Although recent studies have pointed to the existence of additional Laverania species, their precise number and host associations remain uncertain, primarily because of limited sampling and a paucity of parasite sequences other than from mitochondrial DNA. To address this, we used limiting dilution polymerase chain reaction to amplify additional parasite sequences from a large number of chimpanzee and gorilla blood and fecal samples collected at two sanctuaries and 30 field sites across equatorial Africa. Phylogenetic analyses of more than 2,000 new sequences derived from the mitochondrial, nuclear, and apicoplast genomes revealed six divergent and well-supported clades within the Laverania parasite group. Although two of these clades exhibited deep subdivisions in phylogenies estimated from organelle gene sequences, these sublineages were geographically defined and not present in trees from four unlinked nuclear loci. This greatly expanded sequence data set thus confirms six, and not seven or more, ape Laverania species, of which P. reichenowi, Plasmodium gaboni, and Plasmodium billcollinsi only infect chimpanzees, whereas Plasmodium praefalciparum, Plasmodium adleri, and Pladmodium blacklocki only infect gorillas. The new sequence data also confirm the P. praefalciparum origin of human P. falciparum. PMID:27289102

  11. The evolutionary host switches of Polychromophilus: a multi-gene phylogeny of the bat malaria genus suggests a second invasion of mammals by a haemosporidian parasite

    Directory of Open Access Journals (Sweden)

    Witsenburg Fardo

    2012-02-01

    Full Text Available Abstract Background The majority of Haemosporida species infect birds or reptiles, but many important genera, including Plasmodium, infect mammals. Dipteran vectors shared by avian, reptilian and mammalian Haemosporida, suggest multiple invasions of Mammalia during haemosporidian evolution; yet, phylogenetic analyses have detected only a single invasion event. Until now, several important mammal-infecting genera have been absent in these analyses. This study focuses on the evolutionary origin of Polychromophilus, a unique malaria genus that only infects bats (Microchiroptera and is transmitted by bat flies (Nycteribiidae. Methods Two species of Polychromophilus were obtained from wild bats caught in Switzerland. These were molecularly characterized using four genes (asl, clpc, coI, cytb from the three different genomes (nucleus, apicoplast, mitochondrion. These data were then combined with data of 60 taxa of Haemosporida available in GenBank. Bayesian inference, maximum likelihood and a range of rooting methods were used to test specific hypotheses concerning the phylogenetic relationships between Polychromophilus and the other haemosporidian genera. Results The Polychromophilus melanipherus and Polychromophilus murinus samples show genetically distinct patterns and group according to species. The Bayesian tree topology suggests that the monophyletic clade of Polychromophilus falls within the avian/saurian clade of Plasmodium and directed hypothesis testing confirms the Plasmodium origin. Conclusion Polychromophilus' ancestor was most likely a bird- or reptile-infecting Plasmodium before it switched to bats. The invasion of mammals as hosts has, therefore, not been a unique event in the evolutionary history of Haemosporida, despite the suspected costs of adapting to a new host. This was, moreover, accompanied by a switch in dipteran host.

  12. Structural mapping of the ClpB ATPases of Plasmodium falciparum: Targeting protein folding and secretion for antimalarial drug design.

    Science.gov (United States)

    AhYoung, Andrew P; Koehl, Antoine; Cascio, Duilio; Egea, Pascal F

    2015-09-01

    Caseinolytic chaperones and proteases (Clp) belong to the AAA+ protein superfamily and are part of the protein quality control machinery in cells. The eukaryotic parasite Plasmodium falciparum, the causative agent of malaria, has evolved an elaborate network of Clp proteins including two distinct ClpB ATPases. ClpB1 and ClpB2 are involved in different aspects of parasitic proteostasis. ClpB1 is present in the apicoplast, a parasite-specific and plastid-like organelle hosting various metabolic pathways necessary for parasite growth. ClpB2 localizes to the parasitophorous vacuole membrane where it drives protein export as core subunit of a parasite-derived protein secretion complex, the Plasmodium Translocon of Exported proteins (PTEX); this process is central to parasite virulence and survival in the human host. The functional associations of these two chaperones with parasite-specific metabolism and protein secretion make them prime drug targets. ClpB proteins function as unfoldases and disaggregases and share a common architecture consisting of four domains-a variable N-terminal domain that binds different protein substrates, followed by two highly conserved catalytic ATPase domains, and a C-terminal domain. Here, we report and compare the first crystal structures of the N terminal domains of ClpB1 and ClpB2 from Plasmodium and analyze their molecular surfaces. Solution scattering analysis of the N domain of ClpB2 shows that the average solution conformation is similar to the crystalline structure. These structures represent the first step towards the characterization of these two malarial chaperones and the reconstitution of the entire PTEX to aid structure-based design of novel anti-malarial drugs. PMID:26130467

  13. Avian haemosporidian parasites (Haemosporida): A comparative analysis of different polymerase chain reaction assays in detection of mixed infections.

    Science.gov (United States)

    Bernotienė, Rasa; Palinauskas, Vaidas; Iezhova, Tatjana; Murauskaitė, Dovilė; Valkiūnas, Gediminas

    2016-04-01

    Mixed infections of different species and genetic lineages of haemosporidian parasites (Haemosporida) predominate in wildlife, and such infections are particularly virulent. However, currently used polymerase chain reaction (PCR)-based detection methods often do not read mixed infections. Sensitivity of different PCR assays in detection of mixed infections has been insufficiently tested, but this knowledge is essential in studies addressing parasite diversity in wildlife. Here, we applied five different PCR assays, which are broadly used in wildlife avian haemosporidian research, and compared their sensitivity in detection of experimentally designed mixed infections of Haemoproteus and Plasmodium parasites. Three of these PCR assays use primer sets that amplify fragments of cytochrome b gene (cyt b), one of cytochrome oxidase subunit I (COI) gene, and one target apicoplast genome. We collected blood from wild-caught birds and, using microscopic and PCR-based methods applied in parallel, identified single infections of ten haemosporidian species with similar parasitemia. Then, we prepared 15 experimental mixes of different haemosporidian parasites, which often are present simultaneously in wild birds. Similar concentration of total DNA was used in each parasite lineage during preparation of mixes. Positive amplifications were sequenced, and the presence of mixed infections was reported by visualising double-base calling in sequence electropherograms. This study shows that the use of each single PCR assay markedly underestimates biodiversity of haemosporidian parasites. The application of at least 3 PCR assays in parallel detected the majority, but still not all lineages present in mixed infections. We determined preferences of different primers in detection of parasites belonging to different genera of haemosporidians during mixed infections. PMID:26821298

  14. Plasmodium delichoni n. sp.: description, molecular characterisation and remarks on the exoerythrocytic merogony, persistence, vectors and transmission.

    Science.gov (United States)

    Valkiūnas, Gediminas; Ilgūnas, Mikas; Bukauskaitė, Dovilė; Žiegytė, Rita; Bernotienė, Rasa; Jusys, Vytautas; Eigirdas, Vytautas; Fragner, Karin; Weissenböck, Herbert; Iezhova, Tatjana A

    2016-07-01

    Malaria parasite Plasmodium (Novyella) delichoni n. sp. (Haemosporida, Plasmodiidae) was found in a widespread Eurasian songbird, the common house martin Delichon urbicum (Hirundinidae). It is described based on the morphology of its blood stages and segments of the mitochondrial cytochrome b and apicoplast genes, which can be used for molecular identification of this species. Erythrocytic meronts and gametocytes are strictly nucleophilic, and mature gametocytes possess pigment granules of markedly variable size, including large ones (1 μm in length). Due to these features, P. delichoni can be readily distinguished from all described species of avian malaria parasites belonging to subgenus Novyella. Additionally, mature erythrocytic merozoites contain a dense clump of chromatin, a rare character in avian malaria parasites. Erythrocytic merogony is asynchronous. Illustrations of blood stages of the new species are given, and phylogenetic analysis identifies DNA lineages closely related to this parasite. Domestic canary Serinus canaria and Eurasian siskin Carduelis spinus were infected after subinoculation of infected blood obtained from the house martin. Parasitemia was long lasting in both these hosts, but it was high (up to 70 %) in Eurasian siskins and low (up to 1 %) in canaries. Mortality was not observed, and histological examination and chromogenic in situ hybridisation did not reveal secondary exoerythrocytic meronts (phanerozoites) in the exposed birds. It is likely that persistence of this infection occurs due to long-lasting parasitemia in avian hosts. Sporogony was abortive in mosquitoes Culex pipiens pipiens form molestus, Culex quinquefasciatus and Aedes aegypti at gametogenesis or ookinete stages. The new species is absent from juvenile birds at breeding sites in Europe, indicating that transmission occurs at African wintering grounds. PMID:27000087

  15. Genetic characterization of Toxoplasma gondii isolates in dogs from Vietnam suggests their South American origin.

    Science.gov (United States)

    Dubey, J P; Huong, Lam Thi Thu; Sundar, N; Su, C

    2007-05-31

    Dogs are considered a potential risk for transmission of Toxoplasma gondii to humans because they can mechanically transmit oocysts to people and in certain parts of the world dog meat is consumed by humans. The prevalence of T. gondii in 42 dogs from rural Vietnam was determined. Antibodies to T. gondii were assayed by the modified agglutination test, and found in 21 (50%) of 42 dogs with titers of 1:20 in six, 1:40 in seven, 1:80 in two, 1:160 in two, 1:320 in two, 1:640 in one, and 1:1280 or higher in one. Hearts, tongues and brains of 21 seropositive dogs were bioassayed in cats, mice or both. Tissues from eight seropositive dogs were fed to eight T. gondii-free cats. Feces of cats were examined for oocysts. T. gondii was isolated from eight dogs by bioassay in cats. Genotyping of these eight T. gondii isolates using polymorphisms at 10 nuclear markers including SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and a new SAG2, and an apicoplast marker Apico revealed two genotypes. Both genotypes were previously identified from the dog isolates in Colombia, suggesting their South America origin. However, they are different from the predominant Type I, II and III lineages that are widely spread in North America and Europe. This is the first report of isolation of viable T. gondii from any host in Vietnam. PMID:17442492

  16. [Genomic, molecular biology and malaria: new medical perspectives?].

    Science.gov (United States)

    Ambroise-Thomas, P

    2004-08-01

    The knowledge of genomic structure of man, of Plasmodium falciparum and of its main vector Anopheles gambiae has led to great progress in the understanding of malaria pathophysiology. It may also offer new perspectives for malaria therapy vaccines or control of mosquito-borne transmission. In pathophysiology, genes encoding adhesion plasmodial proteins of their receptors were identified, as well as other genes controlling the patient immune response or the antigenic parasite variability. From a therapeutic point of view, new targets for future antimalarial drugs were identified, mainly in apicoplast (a vestige of vegetal structure incorporated by the parasite during its phylogenic evolution) and several enzymes, particularly proteases. It will be now necessary among these "promising new molecules" to select a few ones (probably no more than 5 or 6) for a pre clinical and clinical pharmaceutical development. Indeed, the industrial possibilities for developing new antimalarial drugs are evidently limited and several other antimalarial drugs are already under development. For future malaria vaccines, several new targets and antigenic proteins were also identified. As for new drugs, a complete evaluation of these antigens is absolutely necessary to select few of them for clinical development. Particularly for malaria, ADN vaccines may offer very promising perspectives with the possibility to obtain both humoral and cellular immunity and to use at the same time a panel of plasmodial antigens. It could be thus possible to obtain a simultaneous immunization against different stages of Plasmodium falciparum (sporozoites, merozoites, gametocytes) and to use, as an adjuvant, a gene encoding a viral protein or a cytokine (GMCSF). In Anopheles gambiae genome, several genes encoding for key-proteins, particularly odorant receptors necessary for blood meals, were identified. Non biting-non transmitting mosquitoes were obtained by genetic manipulation and, from an academic