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Abstract
Complement-dependent destruction of invading micro-organisms is a crucial first-line defense against infection, yet both African and American trypanosomes are able to resist attack by complement. African trypanosomes resist non-specific complement attack by virtue of a thick glycoprotein surface coat, and the host range of certain African trypanosomes is believed to be defined by their susceptibility to a subclass of human high density lipoprotein (HDL) and/or a high molecular weight protein complex present in human serum. In the first part of this review, Stephen Tomlinson and Jayne Raper look at the properties and mechanisms of action of these trypanolytic factors on African trypanosomes, and discuss briefly the possible mechanisms whereby these human pathogens resist lysis by human serum. The mechanisms that enable the American trypanosome Trypanosoma cruzi to resist complement attack are reviewed in the second part of this article.
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Affiliation(s)
- S Tomlinson
- Department of Pathology, New York University Medical Center, New York, NY 10016, USA
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2
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Faulkner SD, Oli MW, Kieft R, Cotlin L, Widener J, Shiflett A, Cipriano MJ, Pacocha SE, Birkeland SR, Hajduk SL, McArthur AG. In vitro generation of human high-density-lipoprotein-resistant Trypanosoma brucei brucei. EUKARYOTIC CELL 2007; 5:1276-86. [PMID: 16896212 PMCID: PMC1539141 DOI: 10.1128/ec.00116-06] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The host range of African trypanosomes is influenced by innate protective molecules in the blood of primates. A subfraction of human high-density lipoprotein (HDL) containing apolipoprotein A-I, apolipoprotein L-I, and haptoglobin-related protein is toxic to Trypanosoma brucei brucei but not the human sleeping sickness parasite Trypanosoma brucei rhodesiense. It is thought that T. b. rhodesiense evolved from a T. b. brucei-like ancestor and expresses a defense protein that ablates the antitrypanosomal activity of human HDL. To directly investigate this possibility, we developed an in vitro selection to generate human HDL-resistant T. b. brucei. Here we show that conversion of T. b. brucei from human HDL sensitive to resistant correlates with changes in the expression of the variant surface glycoprotein (VSG) and abolished uptake of the cytotoxic human HDLs. Complete transcriptome analysis of the HDL-susceptible and -resistant trypanosomes confirmed that VSG switching had occurred but failed to reveal the expression of other genes specifically associated with human HDL resistance, including the serum resistance-associated gene (SRA) of T. b. rhodesiense. In addition, we found that while the original active expression site was still utilized, expression of three expression site-associated genes (ESAG) was altered in the HDL-resistant trypanosomes. These findings demonstrate that resistance to human HDLs can be acquired by T. b. brucei.
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Affiliation(s)
- Sara D Faulkner
- Josephine Bay Paul Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USA
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3
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Vanhamme L, Pays E. The trypanosome lytic factor of human serum and the molecular basis of sleeping sickness. Int J Parasitol 2004; 34:887-98. [PMID: 15217727 DOI: 10.1016/j.ijpara.2004.04.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2004] [Revised: 04/20/2004] [Accepted: 04/20/2004] [Indexed: 02/08/2023]
Abstract
Trypanosoma brucei brucei infects a wide range of mammals but is unable to infect humans because this subspecies is lysed by normal human serum (NHS). The trypanosome lytic factor is associated with High Density Lipoproteins (HDLs). Several HDL-associated components have been proposed as candidate lytic factors, and contradictory hypotheses concerning the mechanism of lysis have been suggested. Elucidation of the process by which Trypanosoma brucei rhodesiense resists lysis and causes human sleeping sickness has indicated that the HDL-bound apolipoprotein L-I (apoL-I) could be the long-sought after lytic component of NHS. This research also allowed the identification of a specific diagnostic DNA probe for T. b. rhodesiense, and may lead to the development of novel anti-trypanosome strategies for use in the field.
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Affiliation(s)
- Luc Vanhamme
- Department of Molecular Biology, Laboratory of Molecular Parasitology, IBMM, University of Brussels, 12, rue des Professeurs Jeener et Brachet, B6041 Gosselies, Belgium
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4
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Raper J, Portela Molina MP, Redpath M, Tomlinson S, Lugli E, Green H. Natural immunity to human African trypanosomiasis: trypanosome lytic factors and the blood incubation infectivity test. Trans R Soc Trop Med Hyg 2002; 96 Suppl 1:S145-50. [PMID: 12055829 DOI: 10.1016/s0035-9203(02)90067-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
This review focuses on the epidemiology of human African trypanosomiasis: why it occurs in humans, the current methods of surveillance, and the drugs available to treat it. Emphasis is placed on the identification of human-infective trypanosomes by the blood incubation infectivity test. This test distinguishes between trypanosomes that are non-infective for humans and those that are potentially infective. Currently the test requires incubation of parasites with human serum before injection into mice; any surviving parasites are considered human-infective. The factors in serum that kill all non-human-infective parasites are known as trypanosome lytic factors. The paper details the biochemistry of these factors and recommends standardization of the test based on current knowledge. This test can be used to screen animals with trypanosomiasis, in order to evaluate their role during endemic and epidemic human African trypanosomiasis.
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Affiliation(s)
- Jayne Raper
- Departments of Medical and Molecular Parasitology and Pathology, New York University School of Medicine, 341 East 25th Street, New York, NY 10010, USA.
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5
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Bishop JR, Shimamura M, Hajduk SL. Insight into the mechanism of trypanosome lytic factor-1 killing of Trypanosoma brucei brucei. Mol Biochem Parasitol 2001; 118:33-40. [PMID: 11704271 DOI: 10.1016/s0166-6851(01)00361-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
It has been known for almost a century that normal human serum can lyse the extracellular blood parasite Trypanosoma brucei brucei. This process is a result of a non-immune killing factor in human sera known as trypanosome lytic factor (TLF). In this work, we demonstrate that killing of T. b. brucei by trypanosome lytic factor-1 (TLF-1) in vitro is inhibited by the lipophyllic iron chelator, LI, the lipophyllic antioxidant DPPD, and the protease inhibitors antipain and E64. Thus TLF-1 killing likely requires iron, oxidants, and serine and cysteine proteases. Furthermore, we demonstrate that TLF-1 mediated lysis causes measurable peroxidation in T. brucei lipids via a reaction that is inhibited by DPPD, weak bases, and human haptoglobin. We hypothesize that TLF-1 lysis requires intracellular factors within the trypanosome including high intracellular H2O2 and high polyenoic lipid concentrations, lysosomal acidification and proteases, and intracellular iron sources. The data presented supports the hypothesis that the combination of these factors with TLF-1 inside the lysosome results in lysosomal membrane breakdown, release of the lysosomal contents, and subsequent autodigestion of the cell.
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Affiliation(s)
- J R Bishop
- Department of Biochemistry and Molecular Genetics, Schools of Medicine and Dentistry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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6
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Abstract
The review discusses the current field status of human and bovine trypanosomiases, and focuses on the molecular basis of innate and acquired control of African trypanosomes in people, cattle, and Cape buffalo.
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Affiliation(s)
- S J Black
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst 01003, USA
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7
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Milner JD, Hajduk SL. Expression and localization of serum resistance associated protein in Trypanosoma brucei rhodesiense. Mol Biochem Parasitol 1999; 104:271-83. [PMID: 10593181 DOI: 10.1016/s0166-6851(99)00151-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The trypanosome lytic factor (TLF) is a primate specific innate defense mechanism that restricts the host range of African trypanosomes. Trypanosoma brucei rhodesiense, the causative agent of the acute form of human sleeping sickness, is resistant to the cytolytic action of TLF. By differential display PCR we have identified a gene in T. b. rhodesiense that is preferentially expressed in cell lines resistant to TLF. The protein sequence predicted from the gene shows homology to the trypanosome variable surface glycoprotein (VSG) gene family and in particular, to the previously reported human serum resistance associated gene (SRA). The amount of SRA mRNA is over 1000-fold higher in TLF resistant cells relative to TLF sensitive trypanosomes. Treatment of TLF sensitive trypanosomes with increasing concentrations of TLF in mice results in the selection of parasites that have reverted back to the TLF resistant phenotype. These trypanosomes also showed high levels of SRA mRNA. Antibodies against recombinant SRA react with a 59 kDa protein on western blots of total cell protein from TLF resistant trypanosomes but not TLF sensitive cells. Indirect immunofluorescence revealed that SRA is a cell surface protein present only in TLF resistant trypanosomes. These results suggest that TLF resistance in human sleeping sickness trypanosomes is a consequence of the selective, high level expression of a cell surface molecule(s). In addition, these studies support the role of TLF as a major factor in human serum mediated killing of susceptible trypanosomes.
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Affiliation(s)
- J D Milner
- Department of Biochemistry and Molecular Genetics, School of Medicine and Dentistry, University of Alabama at Birmingham, 35294, USA
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8
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Raper J, Fung R, Ghiso J, Nussenzweig V, Tomlinson S. Characterization of a novel trypanosome lytic factor from human serum. Infect Immun 1999; 67:1910-6. [PMID: 10085035 PMCID: PMC96545 DOI: 10.1128/iai.67.4.1910-1916.1999] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Natural resistance of humans to the cattle pathogen Trypanosoma brucei brucei has been attributed to the presence in human serum of nonimmune factors that lyse the parasite. Normal human serum contains two trypanosome lytic factors (TLFs). TLF1 is a 500-kDa lipoprotein, which is reported to contain apolipoprotein A-I (apoA-I), haptoglobin-related protein (Hpr), hemoglobin, paraoxonase, and apoA-II, whereas TLF2 is a larger, poorly characterized particle. We report here a new immunoaffinity-based purification procedure for TLF2 and TLF1, as well as further characterization of the components of each purified TLF. Immunoaffinity-purified TLF1 has a specific activity 10-fold higher than that of TLF1 purified by previously described methods. Moreover, we find that TLF1 is a lipoprotein particle that contains mainly apoA-I and Hpr, trace amounts of paraoxonase, apoA-II, and haptoglobin, but no detectable hemoglobin. Characterization of TLF2 reveals that it is a 1,000-kDa protein complex containing mainly immunoglobulin M, apoA-I, and Hpr but less than 1% detectable lipid.
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Affiliation(s)
- J Raper
- Departments of Medical and Molecular Parasitology, New York University Medical School, New York, New York 10010, USA.
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9
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Abstract
The history of human sleeping sickness in East Africa is characterized by the appearance of disease epidemics interspersed by long periods of endemicity. Despite the presence of the tsetse fly in large areas of East Africa, these epidemics tend to occur multiply in specific regions or foci rather than spreading over vast areas. Many theories have been proposed to explain this phenomenon, but recent molecular approaches and detailed analyses of epidemics have highlighted the stability of human-infective trypanosome strains within these foci. The new molecular data, taken alongside the history and biology of human sleeping sickness, are beginning to highlight the important factors involved in the generation of epidemics. Specific, human-infective trypanosome strains may be associated with each focus, which, in the presence of the right conditions, can be responsible for the generation of an epidemic. Changes in agricultural practice, favoring the presence of tsetse flies, and the important contribution of domestic animals as a reservoir for the parasite are key factors in the maintenance of such epidemics. This review examines the contribution of molecular and genetic data to our understanding of the epidemiology and history of human sleeping sickness in East Africa.
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Affiliation(s)
- G Hide
- Centre for Molecular Epidemiology and Ecology, Department of Biological Sciences, University of Salford, Salford M5 4WT, United Kingdom.
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Tomlinson S, Muranjan M, Nussenzweig V, Raper J. Haptoglobin-related protein and apolipoprotein AI are components of the two trypanolytic factors in human serum. Mol Biochem Parasitol 1997. [DOI: 10.1016/s0166-6851(97)02844-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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Abstract
Trypanosoma brucei brucei, the causative agent of ngana in cattle, is non-infectious to humans because of its sensitivity to the cytolytic activity of normal human serum. The toxin in normal human serum is human haptoglobin-related protein (Hpr) which is found either as an apolipoprotein associated with a minor subclass of high-density lipoprotein (HDL), named trypanosome lytic factor (TLF1), or as an unstable, high-molecular-mass protein complex known as TLF2 (refs 5, 9-12). TLF-mediated lysis of T. b. brucei requires binding, internalization and lysosomal targeting. The human sleeping-sickness trypanosome, Trypanosoma brucei rhodesiense is resistant to TLF. Our studies reveal that resistant trypanosomes fail to endocytose TLF yet continue to bind TLF through cell-surface receptors. On the basis of these results, we conclude that one mechanism of resistance of human sleeping-sickness trypanosomes to human serum is decreased internalization of receptor-bound TLF.
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Affiliation(s)
- K M Hager
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Schools of Medicine and Dentistry, 35294-0005, USA
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12
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Abstract
The natural immunity of humans to the cattle pathogen Trypanosoma brucei brucei, but not to the morphologically indistinguishable human pathogens T. brucei gambiense and T. brucei rhodesiense, is due to the selective killing of the parasite by normal human serum. The factor in human serum that mediates lysis of T. brucei brucei has long been attributed to a minor subclass of high density lipoprotein (HDL). Evidence indicates that the trypanolytic activity of isolated human HDL is due to peroxidase activity of an associated haptoglobin-related protein-hemoglobin complex. However, recent data suggest that the trypanolytic activity of HDL may be completely inhibited in whole human serum, and that trypanolytic activity of norman human serum is due to a second, less well-defined factor of high molecular weight. Current research aimed at understanding the mechanisms of cytotoxicity and the affected metabolic pathways may open new approaches for the development of specific drugs and vaccines against trypanosomiasis.
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Affiliation(s)
- S Tomlinson
- Department of Pathology, NYU Medical Center, New York 10016, USA.
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13
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Owen JS, Lorenz P, Betschart B. HDL particles as the trypanosome-killing factor in human serum: An exclusive or inconclusive role? ACTA ACUST UNITED AC 1996; 12:250-1. [PMID: 15275208 DOI: 10.1016/0169-4758(96)80814-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Raper J, Nussenzweig V, Tomlinson S. The main lytic factor of Trypanosoma brucei brucei in normal human serum is not high density lipoprotein. J Exp Med 1996; 183:1023-9. [PMID: 8642243 PMCID: PMC2192309 DOI: 10.1084/jem.183.3.1023] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Natural immunity of humans to the cattle pathogen Trypanosoma brucei brucei has been attributed to the presence in normal human serum (NHS) of lytic factors for the parasites. We and others have shown that NHS contains two trypanolytic factors (herein termed TLF1 and TLF2) that can be separated by gel filtration. TLF1 copurifies with a subclass of high density lipoprotein (HDL), whereas TLF2 has a much higher molecular weight and does not appear to be a lipoprotein. We find that the trypanolytic activity of purified TLF1 is totally inhibited by exogenous haptoglobin (Hp) at concentrations (0.1 mg/ml) lower than those present in NHS (0.2-2 mg/ml). In contrast, exogenous Hp (up to 2.5 mg/ml) has no effect on the lytic activity of either NHS or isolated TLF2. Hp-depleted sera from patients with intravascular hemolysis is severalfold more trypanolytic than NHS. These sera contain only TLF1, and their lytic activity is totally abolished upon the addition of Hp (0.1 mg/ml). When NHS containing different Hp allotypes is fractionated by gel filtration, TLF1 activity is either revealed or remains masked, depending on whether it coelutes with Hp. Masked TLF1 activity in the column fractions is revealed if Hp is removed by density gradient ultracentrifugation. We conclude that endogenous Hp inhibits TLF1 activity, and that TLF2 is the main trypanolytic factor in NHS.
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Affiliation(s)
- J Raper
- Department of Medical and Biochemical Parasitology, New York University Medical School, New York 10016, USA
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15
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Raper J, Nussenzweig V, Tomlinson S. Lack of correlation between haptoglobin concentration and trypanolytic activity of normal human serum. Mol Biochem Parasitol 1996; 76:337-8. [PMID: 8920024 DOI: 10.1016/0166-6851(95)02551-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- J Raper
- Department of Medical and Biochemical Parasitology, New York University Medical Center, New York 10016, USA
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16
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17
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Smith AB, Hajduk SL. Identification of haptoglobin as a natural inhibitor of trypanocidal activity in human serum. Proc Natl Acad Sci U S A 1995; 92:10262-6. [PMID: 7479764 PMCID: PMC40776 DOI: 10.1073/pnas.92.22.10262] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Trypanosomes are protozoan parasites of medical and veterinary importance. Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense infect humans, causing African sleeping sickness. However, Trypanosoma brucei brucei can only infect animals, causing the disease Nagana in cattle. Man is protected from this subspecies of trypanosomes by a toxic subtype of high density lipoproteins (HDLs) called the trypanosome lytic factor (TLF). The toxic molecule in TLF is believed to be the haptoglobin-related protein that when bound to hemoglobin kills the trypanosome via oxidative damage initiated by its peroxidase activity. The amount of lytic activity in serum varies widely between different individuals with up to a 60-fold difference in activity. In addition, an increase in the total amount of lytic activity occurs during the purification of TLF, suggesting that an inhibitor of TLF (ITLF) exists in human serum. We now show that the individual variation in trypanosome lytic activity in serum correlates to variations in the amount of ITLF. Immunoblots of ITLF probed with antiserum against haptoglobin recognize a 120-kDa protein, indicating that haptoglobin is present in partially purified ITLF. Haptoglobin involvement is further shown in that it inhibits TLF in a manner similar to ITLF. Using an anti-haptoglobin column to remove haptoglobin from ITLF, we show that the loss of haptoglobin coincides with the loss of inhibitor activity. Addition of purified haptoglobin restores inhibitor activity. This indicates that haptoglobin is the molecule responsible for inhibition and therefore causing the individual variation in serum lytic activity.
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Affiliation(s)
- A B Smith
- Department of Biochemistry and Molecular Genetics, School of Medicine and Dentistry, University of Alabama, Birmingham 35294, USA
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18
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Lorenz P, Owen JS, Hassall DG. Human serum resistant Trypanosoma brucei rhodesiense accumulates similar amounts of fluorescently-labelled trypanolytic human HDL3 particles as human serum sensitive T.b. brucei. Mol Biochem Parasitol 1995; 74:113-8. [PMID: 8719251 DOI: 10.1016/0166-6851(95)02479-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- P Lorenz
- Swiss Tropical Institute, Basel, Switzerland.
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19
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Lorenz P, Betschart B, Owen JS. Trypanosoma brucei brucei and high-density lipoproteins: Old and new thoughts on the identity and mechanism of the trypanocidal factor in human serum. ACTA ACUST UNITED AC 1995; 11:348-52. [PMID: 15275320 DOI: 10.1016/0169-4758(95)80191-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Nature has provided humans with a surprising means of protection against the African trypanosome Trypanosoma brucei brucei There is consensus, in that this singular trypanocidal factor is serum high-density lipoproteins (HDL). which the trypanosomes engulf through a physiological, receptor-mediated pathway for delivery to acidic intracellular vesicles. There is also controversy, however, in that the active particles and their essential cytotoxic elements are disputed, in part reflecting the ill-defined mechanism by which the parasites are finally killed. Here Patrick Lorenz, Bruno Betschart and Jim Owen discuss the possibilities for resolving these discrepancies and speculate on the prospects of exploiting this unexpected property of human HDL for protecting livestock.
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Affiliation(s)
- P Lorenz
- Zentrum für Molekulare Biologie, Universität Heidelberg, Postfach 10 62 49, D-69120 Heidelberg, Germany
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20
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Tomlinson S, Jansen AM, Koudinov A, Ghiso JA, Choi-Miura NH, Rifkin MR, Ohtaki S, Nussenzweig V. High-density-lipoprotein-independent killing of Trypanosoma brucei by human serum. Mol Biochem Parasitol 1995; 70:131-8. [PMID: 7637693 DOI: 10.1016/0166-6851(95)00019-w] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The cattle pathogen Trypanosoma brucei brucei is morphologically indistinguishable from the human pathogens T.b. rhodesiense and T.b. gambiense. However, unlike the human pathogens, T.b. brucei is lysed by normal human serum (NHS). The trypanolytic factor in NHS co-purifies with high-density lipoproteins (HDL), but its precise nature is unknown. Using a new fluorescence-based viability assay to assess T.b. brucei killing, we find that the HDL-deficient sera from two patients with Tangier disease are as trypanolytic as NHS. Fractionation of the Tangier sera by density ultracentrifugation revealed that the activity resides only in lipoprotein-depleted fractions. Tangier and NHS were also subjected to molecular sieving chromatography, and the activity profiles were identical. Lytic fractions to T. brucei (but not to T. rhodesiense) appeared under two distinct peaks of 100-600 kDa and > 1000 kDa. Neither peak coincided with the position of the major serum lipoproteins, as determined by cholesterol titrations. The high-molecular-mass peak did not contain the HDL-associated apolipoprotein-A1. Further, we did not find that purified apolipoproteins A1 or J are lytic for the trypanosomes. We conclude that the killing of T. brucei by human serum can be independent of HDL.
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Affiliation(s)
- S Tomlinson
- Michael Heidelberger Division of Immunology, New York University Medical Center, NY 10016, USA
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21
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Lorenz P, Barth PE, Rudin W, Betschart B. Importance of acidic intracellular compartments in the lysis of Trypanosoma brucei brucei by normal human serum. Trans R Soc Trop Med Hyg 1994; 88:487-8. [PMID: 7570851 DOI: 10.1016/0035-9203(94)90443-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
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