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Werb O, Matuschewski K, Weber N, Hillers A, Garteh J, Jusu A, Turay BS, Wauquier N, Escalante AA, Andreína Pacheco M, Schaer J. New member of Plasmodium (Vinckeia) and Plasmodium cyclopsi discovered in bats in Sierra Leone - nuclear sequence and complete mitochondrial genome analyses. Int J Parasitol 2024; 54:475-484. [PMID: 38762159 DOI: 10.1016/j.ijpara.2024.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 04/03/2024] [Accepted: 05/13/2024] [Indexed: 05/20/2024]
Abstract
Malaria remains the most important arthropod-borne infectious disease globally. The causative agent, Plasmodium, is a unicellular eukaryote that develops inside red blood cells. Identifying new Plasmodium parasite species that infect mammalian hosts can shed light on the complex evolution and diversity of malaria parasites. Bats feature a high diversity of microorganisms including seven separate genera of malarial parasites. Three species of Plasmodium have been reported so far, for which scarce reports exist. Here we present data from an investigation of Plasmodium infections in bats in the western Guinean lowland forest in Sierra Leone. We discovered a new Plasmodium parasite in the horseshoe bat Rhinolophus landeri. Plasmodium cyclopsi infections in a member of leaf-nosed bats, Doryrhina cyclops, exhibited a high prevalence of 100%. Phylogenetic analysis of complete mitochondrial genomes and nine nuclear markers recovered a close relationship between P. cyclopsi and the new Plasmodium parasite with the rodent species Plasmodium berghei, a widely used in vivo model to study malaria in humans. The data suggests that the "rodent/bat" Plasmodium (Vinckeia) clade represents a diverse group of malarial parasites that would likely expand with a systematic sampling of small mammals in tropical Africa. Identifying the bat Plasmodium repertoire is central to our understanding of the evolution of Plasmodium parasites in mammals.
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Affiliation(s)
- Oskar Werb
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany
| | - Kai Matuschewski
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany
| | - Natalie Weber
- Max Planck Institute of Animal Behavior, Department of Migration, Radolfzell, Germany; Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Germany
| | - Annika Hillers
- Wild Chimpanzee Foundation (WCF), Monrovia, Liberia; The Royal Society for the Protection of Birds, Centre for Conservation Science, Sandy, United Kingdom
| | - Jerry Garteh
- Society for the Conservation of Nature of Liberia (SCNL), Monrovia, Liberia
| | - Amadu Jusu
- Gola Rainforest Conservation Limited by Guarantee (GRC_LG) Kenema, Sierra Leone
| | - Brima S Turay
- Gola Rainforest Conservation Limited by Guarantee (GRC_LG) Kenema, Sierra Leone
| | - Nadia Wauquier
- Sorbonne Université, Inserm U1135 CNRS EMR 8255, Centre d'Immunologie et des Maladies Infectieuses (CIMI-Paris), Paris, France
| | - Ananias A Escalante
- Biology Department/Institute of Genomics and Evolutionary Medicine (iGEM), Temple University, Philadelphia, PA, USA
| | - M Andreína Pacheco
- Biology Department/Institute of Genomics and Evolutionary Medicine (iGEM), Temple University, Philadelphia, PA, USA
| | - Juliane Schaer
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany; Department of Biological Sciences, Macquarie University, Sydney, Australia; Museum für Naturkunde, Leibniz-Institute for Evolution and Biodiversity Science, Berlin, Germany; Department of Biology, Muni University, Arua, Uganda.
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Rodent malaria in Gabon: Diversity and host range. INTERNATIONAL JOURNAL FOR PARASITOLOGY-PARASITES AND WILDLIFE 2019; 10:117-124. [PMID: 31453086 PMCID: PMC6702409 DOI: 10.1016/j.ijppaw.2019.07.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 07/26/2019] [Accepted: 07/27/2019] [Indexed: 12/26/2022]
Abstract
Malaria parasites infect a wide range of vertebrate hosts, such as reptiles, birds and mammals (i.e., primates, ungulates, bats, and rodents). Four Plasmodium species and their subspecies infect African Muridae. Since their discoveries in the 1940s, these rodent Plasmodium species have served as biological models to explore many aspects of the biology of malaria agents and their interactions with their hosts. Despite that, surprisingly, little is known about their ecology, natural history and evolution. Most field studies on these parasites, performed from the 1940s to the early 1980s, showed that all rodent Plasmodium species infect only one main host species, the thicket rat. In the present study, we re-explored the diversity of Plasmodium parasites infecting rodent species living in peridomestic habitats in Gabon, Central Africa. Using molecular approaches, we found that at least two Plasmodium species (Plasmodium vinckei and Plasmodium yoelii) circulated among five rodent species (including the invasive species Mus musculus). This suggests that the host range of these parasites might be larger than previously considered. Our results also showed that the diversity of these parasites could be higher than currently recognized, with the discovery of a new phylogenetic lineage that could represent a new species of rodent Plasmodium. Circulation of at least two Plasmodium species in multiple rodent species in Gabon. African rodent Plasmodium host range is higher than previously recognized. Existence of a potentially new Plasmodium species (Plasmodium sp GAB), closely related to Plasmodium yoelii.
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Mackinnon MJ, Read AF. GENETIC RELATIONSHIPS BETWEEN PARASITE VIRULENCE AND TRANSMISSION IN THE RODENT MALARIA PLASMODIUM CHABAUDI. Evolution 2017; 53:689-703. [PMID: 28565637 DOI: 10.1111/j.1558-5646.1999.tb05364.x] [Citation(s) in RCA: 149] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/1998] [Accepted: 01/08/1999] [Indexed: 01/22/2023]
Abstract
Many parasites evolve to become virulent rather than benign mutualists. One of the major theoretical models of parasite virulence postulates that this is because rapid within-host replication rates are necessary for successful transmission (parasite fitness) and that virulence (damage to the host) is an unavoidable consequence of this rapid replication. Two fundamental assumptions underlying this so-called evolutionary trade-off model have rarely been tested empirically: (1) that higher replication rates lead to higher levels of virulence; and (2) that higher replication rates lead to higher transmission. Both of these relationships must have a genetic basis for this evolutionary hypothesis to be relevant. These assumptions were tested in the rodent malaria parasite, Plasmodium chabaudi, by examining genetic relationships between virulence and transmission traits across a population of eight parasite clones isolated from the wild. Each clone was injected into groups of inbred mice in a controlled laboratory environment, and replication rate (measured by maximum asexual parasitemia), virulence (measured by live-weight loss and degree of anemia in the mouse), and transmission (measured by density of sexual forms, gametocytes, in the blood and proportion of mosquitoes infected after taking a blood-meal from the mouse) were assessed. It was found that clones differed widely in these traits and these clone differences were repeatable over successive blood passages. Virulence traits were strongly phenotypically and genetically (i.e., across clones) correlated to maximum parasitemia thus supporting the first assumption that rapid replication causes higher virulence. Transmission traits were also positively phenotypically and genetically correlated to parasitemia, which supports the second assumption that rapid replication leads to higher transmission. Thus, two assumptions of the parasite-centered trade-off model of the evolution of virulence were shown to be justified in malaria parasites.
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Affiliation(s)
- Margaret J Mackinnon
- Institute of Cell, Animal and Population Biology, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh, EH9 3JT, United Kingdom
| | - Andrew F Read
- Institute of Cell, Animal and Population Biology, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh, EH9 3JT, United Kingdom
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Karadjian G, Berrebi D, Dogna N, Vallarino-Lhermitte N, Bain O, Landau I, Martin C. Co-infection restrains Litomosoides sigmodontis filarial load and plasmodial P. yoelii but not P. chabaudi parasitaemia in mice. ACTA ACUST UNITED AC 2014; 21:16. [PMID: 24717449 PMCID: PMC3980669 DOI: 10.1051/parasite/2014017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 03/26/2014] [Indexed: 01/19/2023]
Abstract
Infection with multiple parasite species is clearly the norm rather than the exception, in animals as well as in humans. Filarial nematodes and Plasmodium spp. are important parasites in human public health and they are often co-endemic. Interactions between these parasites are complex. The mechanisms underlying the modulation of both the course of malaria and the outcome of filarial infection are poorly understood. Despite increasing activity in recent years, studies comparing co- and mono-infections are very much in their infancy and results are contradictory at first sight. In this study we performed controlled and simultaneous co-infections of BALB/c mice with Litomosoides sigmodontis filaria and with Plasmodium spp. (Plasmodium yoelii 17 XNL or Plasmodium chabaudi 864VD). An analysis of pathological lesions in the kidneys and lungs and a parasitological study were conducted at different times of infection. Whatever the plasmodial species, the filarial recovery rate was strongly decreased. The peak of parasitaemia in the plasmodial infection was decreased in the course of P. yoelii infection but not in that of P. chabaudi. Regarding pathological lesions, L. sigmodontis can reverse lesions in the kidneys due to the presence of both Plasmodium species but does not modify the course of pulmonary lesions. The filarial infection induces granulomas in the lungs.
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Affiliation(s)
- Gregory Karadjian
- UMR 7245 MCAM MNHN CNRS, Muséum National d'Histoire Naturelle, 61 rue Buffon, CP 52, 75231 Paris Cedex 05, France
| | - Dominique Berrebi
- Service d'Anatomie et de Cytologie Pathologique, Paris, Hôpital Robert Debré, Assistance Publique-Hôpitaux de Paris France, and EA3102, Université Paris 7, France
| | - Nathalie Dogna
- UMR 7245 MCAM MNHN CNRS, Muséum National d'Histoire Naturelle, 61 rue Buffon, CP 52, 75231 Paris Cedex 05, France
| | - Nathaly Vallarino-Lhermitte
- UMR 7245 MCAM MNHN CNRS, Muséum National d'Histoire Naturelle, 61 rue Buffon, CP 52, 75231 Paris Cedex 05, France
| | - Odile Bain
- UMR 7245 MCAM MNHN CNRS, Muséum National d'Histoire Naturelle, 61 rue Buffon, CP 52, 75231 Paris Cedex 05, France
| | - Irène Landau
- UMR 7245 MCAM MNHN CNRS, Muséum National d'Histoire Naturelle, 61 rue Buffon, CP 52, 75231 Paris Cedex 05, France
| | - Coralie Martin
- UMR 7245 MCAM MNHN CNRS, Muséum National d'Histoire Naturelle, 61 rue Buffon, CP 52, 75231 Paris Cedex 05, France
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Stephens R, Culleton RL, Lamb TJ. The contribution of Plasmodium chabaudi to our understanding of malaria. Trends Parasitol 2011; 28:73-82. [PMID: 22100995 DOI: 10.1016/j.pt.2011.10.006] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 10/17/2011] [Accepted: 10/18/2011] [Indexed: 12/23/2022]
Abstract
Malaria kills close to a million people every year, mostly children under the age of five. In the drive towards the development of an effective vaccine and new chemotherapeutic targets for malaria, field-based studies on human malaria infection and laboratory-based studies using animal models of malaria offer complementary opportunities to further our understanding of the mechanisms behind malaria infection and pathology. We outline here the parallels between the Plasmodium chabaudi mouse model of malaria and human malaria. We will highlight the contribution of P. chabaudi to our understanding of malaria in particular, how the immune response in malaria infection is initiated and regulated, its role in pathology, and how immunological memory is maintained. We will also discuss areas where new tools have opened up potential areas of exploration using this invaluable model system.
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Affiliation(s)
- Robin Stephens
- University of Texas Medical Branch, Departments of Microbiology and Immunology and Internal Medicine, Division of Infectious Diseases, 301 University Boulevard, Galveston, TX 77555-0435, USA
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Poudel SS, Newman RA, Vaughan JA. Rodent Plasmodium: population dynamics of early sporogony within Anopheles stephensi mosquitoes. J Parasitol 2009; 94:999-1008. [PMID: 18576764 DOI: 10.1645/ge-1407.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Accepted: 02/13/2008] [Indexed: 02/05/2023] Open
Abstract
Early sporogony of Plasmodium parasites involves 2 major developmental transitions within the insect vector, i.e., gametocyte-to-ookinete and ookinete-to-oocyst. This study compared the population dynamics of early sporogony among murine rodent Plasmodium (Plasmodium berghei, Plasmodium chabaudi, Plasmodium vinckei, and Plasmodium yoelii) developing within Anopheles stephensi mosquitoes. Estimates of absolute densities were determined for gametocytes, ookinetes, and oocysts for 108 experimental infections. Total losses throughout early sporogony were greatest in P. vinckei (ca. 250,000-fold loss), followed by P. yoelii (ca. 70,000-fold loss), P. berghei (ca. 45,000-fold loss), and P. chabaudi (ca. 15,000-fold loss). The gametocyte-to-ookinete transition represented the most severe population bottleneck. Numerical losses during this transition (ca. 3,000- to 30,000-fold, depending on species) were orders of magnitude greater than losses incurred during the ookinete-to-oocyst transition (3- to 14-fold). There were no significant correlations between gametocyte and ookinete densities. Significant correlations between ookinete and oocyst densities existed for P. berghei, P. chabaudi, and P. yoelii (but not for P. vinckei), and were best described by nonlinear functions (P. berghei = sigmoid, P. chabaudi = hyperbolic, P. yoelii = sigmoid), indicating that conversion of ookinetes to oocysts in these species is density dependent. The upper theoretical limit for oocyst density on the mosquito midgut for P. chabaudi and P. yoelii (ca. 300 oocysts per midgut) was higher than for P. berghei (ca. 30 oocysts per midgut). This study provides basic information about population processes that occur during the early sporogonic development of some common laboratory model systems of malaria.
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Affiliation(s)
- Shreekanta S Poudel
- Department of Biology, University of North Dakota, Grand Forks, North Dakota 58202, USA
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Dietz K, Raddatz G, Molineaux L. Mathematical model of the first wave of Plasmodium falciparum asexual parasitemia in non-immune and vaccinated individuals. Am J Trop Med Hyg 2006; 75:46-55. [PMID: 16931815 DOI: 10.4269/ajtmh.2006.75.46] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
We present a dynamic model of the highly pathogenic first wave of Plasmodium falciparum asexual parasitemia in non-immune persons. The model was successfully fitted to malaria therapy data. This required four case-specific parameters: the basic two-day multiplication factor, the time of onset of adaptive immunity, and the effective dose 50 densities for the innate and adaptive immune responses, respectively. All four parameters show large case-dependent variation that is mainly attributable to host factors. According to the model, the maximum value of the first wave is controlled mainly by the innate immune response. We used the model to explore the expected effects of vaccines targeting the parasite's asexual blood stages on the basis of what we consider to be the biologically most plausible assumptions concerning the parameter modifications induced by vaccination. According to our simulations, the benefit of antiparasitic vaccination is strongly host dependent and vaccine efficacy at low immunogenicity is much larger against severe disease than against fever. This has implications for the early testing of the protective efficacy of a vaccine in humans.
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Affiliation(s)
- Klaus Dietz
- Department of Medical Biometry, University of Tübingen, Tübingen, Germany.
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8
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Barthélémy M, Gabrion C, Petit G. Does chronic malaria modify the odours of its male mouse host? CAN J ZOOL 2005. [DOI: 10.1139/z05-080] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chemical signalling, considered the most important means of communication in rodents, is controlled by the immune and endocrine systems. Several parasitic diseases are associated with modifications of the odour cues deposited by infected male mice and these modifications, conspicuous to sexually receptive females, are supposed to play a role in a parasite-mediated mate choice process. The present study clearly demonstrates, with the use of three different two choice test procedures, that females can discriminate the chemical message from malaria-infected and healthy male mice (Mus musculus L., 1758). Females spent more time sniffing soiled beddings and preputial skin rubbings collected from parasitized males at 15 days post injection and at 15, 22, 29 days post injection, respectively. Also, females could discriminate the overall body odour of a parasitized male at 35 days post injection. The cause of these modifications is discussed with regard to the numerous pathologies previously described in the genital tract of infected males. And the present study, although it avoids drawing any conclusions on a parasite-mediated mate choice under wild conditions, stresses the potential benefit that the parasite may gain from the situation.
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Taylor-Robinson AW. Regulation of immunity to malaria: valuable lessons learned from murine models. ACTA ACUST UNITED AC 2005; 11:334-42. [PMID: 15275315 DOI: 10.1016/0169-4758(95)80186-3] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A major advance in immunology has been the establishment of a framework for analysing how certain immune responses dominate following exposure to a particular pathogen or antigen. CD4(+) T helper (Th) cells can be separated into two major subsets which mediate qualitatively distinct cell-mediated (Th1) and humoral (Th2) immune responses. Immunity to most pathogens can be broadly categorized into a predominant protective response of either type. A characteristic of murine malarias is that primary infections with asexual erythrocytic parasites (the pathogenic stage of the malaria life cycle) generate a host protective immune response with a broad spectrum of Th1- and Th2-type CD4(+) T-cell involvement and so can be examined as models of the interaction of Th1 and Th2 cells during an immune response to an infectious agent. Andrew Taylor-Robinson here describes recent events in the dissection of the mechanisms responsible for the generation of protective immunity to Plasmodium chabaudi chabaudi and other experimental malarias in mice.
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Affiliation(s)
- A W Taylor-Robinson
- Wellcome Laboratories for Experimental Parasitology, University of Glasgow, Bearsden Road, Glasgow, UK.
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Iwalewa EO, Agbani EO. Effects of autacoid inhibitors and of an antagonist on malaria infection in mice. Braz J Med Biol Res 2004; 37:1199-204. [PMID: 15273821 DOI: 10.1590/s0100-879x2004000800010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effects of p-chlorophenylalanine, an inhibitor of serotonin synthesis, indomethacin, an inhibitor of prostaglandin synthesis, cyproheptadine, a serotonin, bradykinin and histamine antagonist, were assessed separately and in combination with chloroquine (CQ) in Vom strains of Swiss albino mice (18-22 g) of either sex infected intraperitoneally with 1 x 10(7) Plasmodium yoelii nigeriensis-induced malaria. As prophylactic, these agents reduced from 31.9 +/- 4.5 to 16.1 +/- 8.1% the level of parasitemia relative to control but had no appreciable activity as curative agents when administered subcutaneously once daily for 4 days after 72 h of parasites innoculum in vivo. However, CQ alone and the combination of these agents with CQ in curative and prophylactic treatments significantly reduced (from 50.3 +/- 5.8 to 4.9 +/- 0.75%) the level of parasitemia (P < 0.05), which was taken only once 72 h after the parasites innoculum. The prophylactic result was shown to produce better results than the curative treatment. The data indicate that inhibitors and an antagonist can reduce the parasitemia load (the extent of damage and the severity of infection) as well as enhance the effects of CQ when combined with it for malaria therapy. The study reveals that the production of autacoids in established infection renders autacoid inhibitors and an antagonist ineffective for radical cure in malarial mice; however, selective inhibition of local hormones implicated in the pathological manifestations of malaria infection by autacoid inhibitors and an antagonist may be a possible pathway to reduce the severity of infection and the associated tissue damage and to enhance the efficacy of available anti-malarials.
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Affiliation(s)
- E O Iwalewa
- Department of Pharmacology, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Nigeria.
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Carvalho LJ, Lenzi HL, Pelajo-Machado M, Oliveira DN, Daniel-Ribeiro CT, Ferreira-da-Cruz MF. Plasmodium berghei: cerebral malaria in CBA mice is not clearly related to plasma TNF levels or intensity of histopathological changes. Exp Parasitol 2000; 95:1-7. [PMID: 10864512 DOI: 10.1006/expr.2000.4508] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Plasmodium berghei ANKA infection in CBA/J mice leads to the development of cerebral malaria (CM) that kills 80-90% of the animals in 6-9 days. This model has been used to study the pathogenesis of CM, which is a major cause of morbidity and mortality in Plasmodium falciparum-infected individuals. The role of cytokines in the induction of CM in the murine model has been well documented, but most studies have been restricted to the peak of neurological manifestations. Here we used a sequential approach to compare mice that developed CM with those that developed no cerebral pathology. Animals were examined for systemic histopathological changes and plasma Tumor Necrosis Factor-alpha (TNF) levels. The objectives were (a) to further determine the importance of factors commonly associated with murine CM-such as elevated levels of TNF and the presence of hemorrhage and vascular plugging-by comparing mice at different stages of infection and/or with different outcomes following infection and (b) to examine the importance of systemic changes-course of parasitemia and histopathological alterations in brain, liver, and lungs-in the development of CM. The data suggest that (a) the clinical manifestation of CM appears to be associated with a wave of merozoite release on days 6-7, (b) murine CM does not present reliable histopathological indicators, (c) there is no topographic association between the occurrence of intravascular plugging and the hemorrhagic foci, (d) monocyte-monocyte and monocyte-endothelial cell adherence were the most expressive histopathological events and were not restricted to brain vessels, (e) blood levels of TNF are not indicative of the local tissue reaction, (f) adhesiveness of monocyte/endothelial cells fluctuate during infection and is dissociated from the lymphocyte homing to the liver, and (g) pulmonary megakaryocytosis (megakaryopoiesis?) is a late event in the lungs.
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Affiliation(s)
- L J Carvalho
- Laboratory of Malaria Research, Department of Immunology, Rio de Janeiro, Brazil
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Braks MA, Anderson RA, Knols BG. Infochemicals in mosquito host selection: human skin microflora and Plasmodium parasites. PARASITOLOGY TODAY (PERSONAL ED.) 1999; 15:409-13. [PMID: 10481153 DOI: 10.1016/s0169-4758(99)01514-8] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The interaction between the African malaria vector Anopheles gambiae and its human host has traditionally been viewed within a bitrophic context, considering only the human and the mosquito. Recently, the influence of the Plasmodium parasite on the interaction has been recognized, because it affects the physiology and/or behaviour of humans and mosquitoes. However, studies on odour-mediated host-seeking behaviour of An. gambiae and other Diptera have provided evidence that a fourth group of organisms should be taken into consideration. Human skin microflora play a role in the production of odorous compounds that might function as kairomones for mosquitoes. Here, Marieta Braks, Rob Anderson and Bart Knols introduce the role of human microflora into the process of odour-mediated host selection and review the interaction in a multipartite context so as to identify research avenues that will enhance our limited knowledge of this aspect of malaria transmission.
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Affiliation(s)
- M A Braks
- Laboratory of Entomology, Wageningen Agricultural University, PO Box 8031, 6700 EH, Wageningen, Netherlands.
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13
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Affiliation(s)
- W Peters
- CABI Bioscience, Tropical Parasitic Diseases Unit, St Albans, Hertfordshire, UK
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Giraldo LE, Grab DJ, Wiser MF. Molecular characterization of a Plasmodium chabaudi erythrocyte membrane-associated protein with glutamate-rich tandem repeats. J Eukaryot Microbiol 1998; 45:528-34. [PMID: 9783454 DOI: 10.1111/j.1550-7408.1998.tb05112.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The malarial parasite dramatically affects the structure and function of the erythrocyte membrane by exporting proteins that specifically interact with the host membrane. This report describes the complete sequence and some biochemical properties of a 93-kDa Plasmodium chabaudi chabaudi protein that interacts with the host erythrocyte membrane. Approximately 40% of the deduced protein sequence consists of tandem repeats of 14 amino acids that are rich in glutamic acid residues. Comparison of the repeat sequences from two different P. c. chabaudi strains derived from the same initial isolate revealed an exact duplication of 294 nucleotides suggesting a recent unequal crossing-over event. However, in spite of this potentially high level of intragenic recombination activity, the repeat sequences from P. c. adami are rather conserved suggesting structural or functional constraints on the protein and tandem repeats. The 93-kDa protein exists in an oligomeric form as revealed by gel filtration chromatography and non-denaturing gel electrophoresis. A predominantly alpha-helical predicted secondary structure and a discrepancy between the estimated molecular sizes determined from non-denaturing gel electrophoresis and gel filtration chromatography suggest that the protein is a long rod-shaped or fibrillar, protein. Attributes shared between the 93-kDa protein, some P. falciparum proteins with glutamate-rich tandem repeats, and cytoskeletal proteins suggest that these parasite proteins function as cytoskeletal proteins that possibly stabilize the erythrocyte membrane.
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Affiliation(s)
- L E Giraldo
- Department of Tropical Medicine, Tulane University School of Public Health, New Orleans, Louisiana 70112, USA
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Taylor LH, Walliker D, Read AF. Mixed-genotype infections of malaria parasites: within-host dynamics and transmission success of competing clones. Proc Biol Sci 1997; 264:927-35. [PMID: 9225482 PMCID: PMC1688430 DOI: 10.1098/rspb.1997.0128] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Mixed-genotype infections of microparasites are common, but almost nothing is known about how competitive interactions within hosts affect the subsequent transmission success of individual genotypes. We investigated changes in the composition of mixed-genotype infections of the rodent malaria Plasmodium chabaudi clones CR and ER by monoclonal antibody analysis of the asexual infection in mice, and by PCR amplification of clone-specific alleles in oocysts sampled from mosquitoes which had fed on these mice. Mixed-clone infections were initiated with a 9:1 ratio of the two clones, with ER as the minority in the first experiment and CR as the minority in the second experiment. When beginning as the majority, clones achieved parasite densities in mice comparable to those achieved in control (single-clone) infections. When they began as the minority, clones were suppressed to less than 10% of control parasitaemias during the early part of the infections. However, in mosquitoes, the frequency of the initially rare clone was substantially greater than it was in mice at the start of the infection or four days prior to the feed. In both experiments, the minority clone in the inocula produced as many, or more, oocysts than it did as a single-clone infection. These experiments show that asexual dominance during most of the infection is poorly correlated to transmission probability, and therefore that the assumption that within-host population size correlates to transmission probability may not be warranted. They also raise the fundamental question of why transmission rates of individual genotypes are often higher from mixed than single-clone infections.
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Affiliation(s)
- L H Taylor
- Institute of Cell, Animal and Population Biology, University of Edinburgh, UK
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