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Yamazaki A, Tanaka Y, Watanabe K, Sato M, Kawazu SI, Kita K, Inoue N, van Rensburg HDJ, N'Da DD, Suganuma K. Prophylactic activity of orally administered dry-heat-sterilized Acremonium egyptiacum against Trypanosoma congolense-induced animal African trypanosomosis. Acta Trop 2024; 254:107185. [PMID: 38494059 DOI: 10.1016/j.actatropica.2024.107185] [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: 11/17/2023] [Revised: 02/08/2024] [Accepted: 03/10/2024] [Indexed: 03/19/2024]
Abstract
Animal African trypanosomosis (AAT) is an important global disease of livestock that causes economic losses of up to 4.5 billion US dollars per year. Thus, eliminating AAT in endemic countries will improve agricultural productivity and economic growth. To prevent AAT, vector control and the development of prophylactic drugs are crucial. Ascofuranone (AF) is a bioactive fungal compound with proven in vitro trypanocidal potency and in vivo treatment efficacy. However, the complex stereoselective synthesis of AF has prevented its cost-effective industrial production. Recently, a genetically modified strain of Acremonium egyptiacum fungus that produces a high yield of AF was developed. Therefore, we hypothesized that the oral administration of the AF-producing fungus itself may be effective against AAT. Hence, this study aimed to evaluate the prophylactic activity of orally administered dry-heat-sterilized A. egyptiacum against Trypanosoma congolense IL3000 infection using a mouse model. The survival rate was significantly prolonged (p = 0.009), and parasitemia was suppressed in all AF-fungus-treated groups (Group 1-9) compared with that in the untreated control group (Group 10). Hence, the trypanocidal activity of AF was retained after dry-heat-sterilization of the AF-producing fungus and that its oral administration effectively prevented AAT. Since AAT is endemic to rural areas with underdeveloped veterinary infrastructure, dry-heat-sterilized A. egyptiacum would be the most cost-effective potential treatment for AAT.
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Affiliation(s)
- Ai Yamazaki
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, 080-8555, Japan
| | - Yusuke Tanaka
- Department of Functional Anatomy and Neuroscience, Asahikawa Medical University, Asahikawa, Hokkaido, 078-8510, Japan
| | - Kenichi Watanabe
- Research Center for Global Agromedicine, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido 080-8555, Japan; Department of Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido 080-8555, Japan
| | - Mayu Sato
- Department of Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido 080-8555, Japan
| | - Shin-Ichiro Kawazu
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, 080-8555, Japan
| | - Kiyoshi Kita
- School of Tropical Medicine and Global Health, Nagasaki University, Sakamoto, Nagasaki 852-8523, Japan
| | - Noboru Inoue
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, 080-8555, Japan
| | - Helena D Janse van Rensburg
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom 2520, South Africa
| | - David D N'Da
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom 2520, South Africa
| | - Keisuke Suganuma
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, 080-8555, Japan; Research Center for Global Agromedicine, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido 080-8555, Japan.
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Peacock L, Kay C, Bailey M, Gibson W. Experimental genetic crosses in tsetse flies of the livestock pathogen Trypanosoma congolense savannah. Parasit Vectors 2024; 17:4. [PMID: 38178172 PMCID: PMC10765672 DOI: 10.1186/s13071-023-06105-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 12/17/2023] [Indexed: 01/06/2024] Open
Abstract
BACKGROUND In tropical Africa animal trypanosomiasis is a disease that has severe impacts on the health and productivity of livestock in tsetse fly-infested regions. Trypanosoma congolense savannah (TCS) is one of the main causative agents and is widely distributed across the sub-Saharan tsetse belt. Population genetics analysis has shown that TCS is genetically heterogeneous and there is evidence for genetic exchange, but to date Trypanosoma brucei is the only tsetse-transmitted trypanosome with experimentally proven capability to undergo sexual reproduction, with meiosis and production of haploid gametes. In T. brucei sex occurs in the fly salivary glands, so by analogy, sex in TCS should occur in the proboscis, where the corresponding portion of the developmental cycle takes place. Here we test this prediction using genetically modified red and green fluorescent clones of TCS. METHODS Three fly-transmissible strains of TCS were transfected with genes for red or green fluorescent protein, linked to a gene for resistance to the antibiotic hygromycin, and experimental crosses were set up by co-transmitting red and green fluorescent lines in different combinations via tsetse flies, Glossina pallidipes. To test whether sex occurred in vitro, co-cultures of attached epimastigotes of one red and one green fluorescent TCS strain were set up and sampled at intervals for 28 days. RESULTS All interclonal crosses of genetically modified trypanosomes produced hybrids containing both red and green fluorescent proteins, but yellow fluorescent hybrids were only present among trypanosomes from the fly proboscis, not from the midgut or proventriculus. It was not possible to identify the precise life cycle stage that undergoes mating, but it is probably attached epimastigotes in the food canal of the proboscis. Yellow hybrids were seen as early as 14 days post-infection. One intraclonal cross in tsetse and in vitro co-cultures of epimastigotes also produced yellow hybrids in small numbers. The hybrid nature of the yellow fluorescent trypanosomes observed was not confirmed by genetic analysis. CONCLUSIONS Despite absence of genetic characterisation of hybrid trypanosomes, the fact that these were produced only in the proboscis and in several independent crosses suggests that they are products of mating rather than cell fusion. The three-way strain compatibility observed is similar to that demonstrated previously for T. brucei, indicating that a simple two mating type system does not apply for either trypanosome species.
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Affiliation(s)
- Lori Peacock
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
- Bristol Veterinary School, University of Bristol, Langford, Bristol, BS40 7DU, UK
| | - Chris Kay
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
| | - Mick Bailey
- Bristol Veterinary School, University of Bristol, Langford, Bristol, BS40 7DU, UK
| | - Wendy Gibson
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK.
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Morrison LJ, Steketee PC, Tettey MD, Matthews KR. Pathogenicity and virulence of African trypanosomes: From laboratory models to clinically relevant hosts. Virulence 2023; 14:2150445. [PMID: 36419235 DOI: 10.1080/21505594.2022.2150445] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
African trypanosomes are vector-borne protozoa, which cause significant human and animal disease across sub-Saharan Africa, and animal disease across Asia and South America. In humans, infection is caused by variants of Trypanosoma brucei, and is characterized by varying rate of progression to neurological disease, caused by parasites exiting the vasculature and entering the brain. Animal disease is caused by multiple species of trypanosome, primarily T. congolense, T. vivax, and T. brucei. These trypanosomes also infect multiple species of mammalian host, and this complexity of trypanosome and host diversity is reflected in the spectrum of severity of disease in animal trypanosomiasis, ranging from hyperacute infections associated with mortality to long-term chronic infections, and is also a main reason why designing interventions for animal trypanosomiasis is so challenging. In this review, we will provide an overview of the current understanding of trypanosome determinants of infection progression and severity, covering laboratory models of disease, as well as human and livestock disease. We will also highlight gaps in knowledge and capabilities, which represent opportunities to both further our fundamental understanding of how trypanosomes cause disease, as well as facilitating the development of the novel interventions that are so badly needed to reduce the burden of disease caused by these important pathogens.
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Affiliation(s)
- Liam J Morrison
- Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, UK
| | - Pieter C Steketee
- Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, UK
| | - Mabel D Tettey
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Keith R Matthews
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
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Yamazaki A, Suganuma K, Tanaka Y, Watanabe K, Kawazu SI, Kita K, Inoue N. Efficacy of oral administration of ascofuranone with and without glycerol against Trypanosoma congolense. Exp Parasitol 2023; 252:108588. [PMID: 37499895 DOI: 10.1016/j.exppara.2023.108588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 06/28/2023] [Accepted: 07/23/2023] [Indexed: 07/29/2023]
Abstract
In many developing countries, trypanosomosis in animals results in the reduction of livestock productivity. Since trypanosomosis is endemic to rural areas where medical and veterinary infrastructure is underdeveloped, development of affordable and easy-to-maintain drugs for treatment and prophylaxis against trypanosomosis is necessary. To this end, in this study, we evaluated the efficacy of oral administration of ascofuranone (AF), with and without glycerol (GOL), against trypanosomosis, using a mouse model. We used T. congolense IL3000, the most virulent animal-infecting trypanosome, and BALB/c mice in this study. Eight mice were assigned to either of Groups 1-7: non-infected, untreated, AF 10, 20, 30, 50, and 100 mg/kg with or without GOL, respectively. In the experiment with AF administered with GOL, survival rates were 0% in Group 2 (untreated) and Group 3 (AF 10 mg/kg), 37.5% in Group 4 (AF 20 mg/kg) and Group 5 (AF 30 mg/kg), 50% in Group 6 (AF 50 mg/kg), and 100% in Group 7 (AF 100 mg/kg). In groups in which AF was administered without GOL, survival rates were 0% in Group 2 (untreated), Group 3 (AF 10 mg/kg), Group 4 (AF 20 mg/kg), Group 5 (AF 30 mg/kg), and Group 6 (AF 50 mg/kg), and 12.5% in Group 7 (AF 100 mg/kg), with one mouse surviving till the end of the observation period. The results of the analysis showed that survival rates were significantly higher in all groups (Groups 3-7) than in the untreated group (Group 2) (p < 0.05). Furthermore, a comparison of groups with or without GOL at the same AF concentration revealed that the survival rate was significantly higher in the group treated with GOL. These results suggest that the treatment efficacy of AF against animal trypanosomosis caused by T. congolense is greater when co-administered with GOL, and that oral administration of AF could be a new therapeutic strategy for animal African trypanosomosis.
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Affiliation(s)
- Ai Yamazaki
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, 080-8555, Japan.
| | - Keisuke Suganuma
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, 080-8555, Japan; Research Center for Global Agromedicine, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, 080-8555, Japan.
| | - Yusuke Tanaka
- Department of Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, 080-8555, Japan.
| | - Kenichi Watanabe
- Research Center for Global Agromedicine, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, 080-8555, Japan; Department of Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, 080-8555, Japan.
| | - Shin-Ichiro Kawazu
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, 080-8555, Japan.
| | - Kiyoshi Kita
- School of Tropical Medicine and Global Health, Nagasaki University, Sakamoto, Nagasaki, 852-8523, Japan; Department of Host-Defense Biochemistry, Institute of Tropical Medicine, Nagasaki University, Nagasaki, 852-8523, Japan.
| | - Noboru Inoue
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, 080-8555, Japan.
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Peacock L, Kay C, Collett C, Bailey M, Gibson W. Development of the livestock pathogen Trypanosoma (Nannomonas) simiae in the tsetse fly with description of putative sexual stages from the proboscis. Parasit Vectors 2023; 16:231. [PMID: 37434196 DOI: 10.1186/s13071-023-05847-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 06/22/2023] [Indexed: 07/13/2023] Open
Abstract
BACKGROUND Tsetse-transmitted African animal trypanosomiasis is recognised as an important disease of ruminant livestock in sub-Saharan Africa, but also affects domestic pigs, with Trypanosoma simiae notable as a virulent suid pathogen that can rapidly cause death. Trypanosoma simiae is widespread in tsetse-infested regions, but its biology has been little studied compared to T. brucei and T. congolense. METHODS Trypanosoma simiae procyclics were cultured in vitro and transfected using protocols developed for T. brucei. Genetically modified lines, as well as wild-type trypanosomes, were transmitted through tsetse flies, Glossina pallidipes, to study T. simiae development in the tsetse midgut, proventriculus and proboscis. The development of proventricular trypanosomes was also studied in vitro. Image and mensural data were collected and analysed. RESULTS A PFR1::YFP line successfully completed development in tsetse, but a YFP::HOP1 line failed to progress beyond midgut infection. Analysis of image and mensural data confirmed that the vector developmental cycles of T. simiae and T. congolense are closely similar, but we also found putative sexual stages in T. simiae, as judged by morphological similarity to these stages in T. brucei. Putative meiotic dividers were abundant among T. simiae trypanosomes in the proboscis, characterised by a large posterior nucleus and two anterior kinetoplasts. Putative gametes and other meiotic intermediates were also identified by characteristic morphology. In vitro development of proventricular forms of T. simiae followed the pattern previously observed for T. congolense: long proventricular trypanosomes rapidly attached to the substrate and shortened markedly before commencing cell division. CONCLUSIONS To date, T. brucei is the only tsetse-transmitted trypanosome with experimentally proven capability to undergo sexual reproduction, which occurs in the fly salivary glands. By analogy, sexual stages of T. simiae or T. congolense are predicted to occur in the proboscis, where the corresponding portion of the developmental cycle takes place. While no such stages have been observed in T. congolense, for T. simiae putative sexual stages were abundant in the tsetse proboscis. Although our initial attempt to demonstrate expression of a YFP-tagged, meiosis-specific protein was unsuccessful, the future application of transgenic approaches will facilitate the identification of meiotic stages and hybrids in T. simiae.
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Affiliation(s)
- Lori Peacock
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
- Bristol Veterinary School, University of Bristol, Langford, Bristol, BS40 7DU, UK
| | - Chris Kay
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
| | - Clare Collett
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
- Pathogen Immunology Group, UK Health Security Agency, Porton Down, Salisbury, SP4 0JG, Wiltshire, UK
| | - Mick Bailey
- Bristol Veterinary School, University of Bristol, Langford, Bristol, BS40 7DU, UK
| | - Wendy Gibson
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK.
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Romero-Ramirez A, Casas-Sánchez A, Autheman D, Duffy CW, Brandt C, Clare S, Harcourt K, André MR, de Almeida Castilho Neto KJG, Teixeira MMG, Machado RZ, Coombes J, Flynn RJ, Wright GJ, Jackson AP. Vivaxin genes encode highly immunogenic, non-variant antigens on the Trypanosoma vivax cell-surface. PLoS Negl Trop Dis 2022; 16:e0010791. [PMID: 36129968 PMCID: PMC9529106 DOI: 10.1371/journal.pntd.0010791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 10/03/2022] [Accepted: 09/06/2022] [Indexed: 12/02/2022] Open
Abstract
Trypanosoma vivax is a unicellular hemoparasite, and a principal cause of animal African trypanosomiasis (AAT), a vector-borne and potentially fatal livestock disease across sub-Saharan Africa. Previously, we identified diverse T. vivax-specific genes that were predicted to encode cell surface proteins. Here, we examine the immune responses of naturally and experimentally infected hosts to these unique parasite antigens, to identify immunogens that could become vaccine candidates. Immunoprofiling of host serum shows that one particular family (Fam34) elicits a consistent IgG antibody response. This gene family, which we now call Vivaxin, encodes at least 124 transmembrane glycoproteins that display quite distinct expression profiles and patterns of genetic variation. We focused on one gene (viv-β8) that encodes one particularly immunogenic vivaxin protein and which is highly expressed during infections but displays minimal polymorphism across the parasite population. Vaccination of mice with VIVβ8 adjuvanted with Quil-A elicits a strong, balanced immune response and delays parasite proliferation in some animals but, ultimately, it does not prevent disease. Although VIVβ8 is localized across the cell body and flagellar membrane, live immunostaining indicates that VIVβ8 is largely inaccessible to antibody in vivo. However, our phylogenetic analysis shows that vivaxin includes other antigens shown recently to induce immunity against T. vivax. Thus, the introduction of vivaxin represents an important advance in our understanding of the T. vivax cell surface. Besides being a source of proven and promising vaccine antigens, the gene family is clearly an important component of the parasite glycocalyx, with potential to influence host-parasite interactions. Animal African trypanosomiasis (AAT) is an important livestock disease throughout sub-Saharan Africa and beyond. AAT is caused by Trypanosoma vivax, among other species, a unicellular parasite that is spread by biting tsetse flies and multiplies in the bloodstream and other tissues, leading to often fatal neurological conditions if untreated. Although concerted drug treatment and vector eradication programmes have succeeded in controlling Human African trypanosomiasis, AAT continues to adversely affect animal health and impede efficient food production and economic development in many less-developed countries. In this study, we attempted to identify parasite surface proteins that stimulated the strongest immune responses in naturally infected animals, as the basis for a vaccine. We describe the discovery of a new, species-specific protein family in T. vivax, which we call vivaxin. We show that one vivaxin protein (VIVβ8) is surface expressed and retards parasite proliferation when used to immunize mice, but does not prevent infection. Nevertheless, we also reveal that vivaxin includes another protein previously shown to induce protective immunity (IFX/VIVβ1). Besides its great potential for novel approaches to AAT control, the vivaxin family is revealed as a significant component of the T. vivax cell surface and may have important, species-specific roles in host interactions.
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Affiliation(s)
- Alessandra Romero-Ramirez
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Aitor Casas-Sánchez
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Delphine Autheman
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
- Department of Biology, Hull York Medical School, York Biomedical Research Institute, University of York, York, United Kingdom
| | - Craig W. Duffy
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Cordelia Brandt
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
| | - Simon Clare
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
| | - Katherine Harcourt
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
| | - Marcos Rogério André
- Department of Pathology, Reproduction and One Health, Faculty of Agrarian and Veterinary Sciences, São Paulo State University (UNESP), Jaboticabal, Sao Paulo, Brazil
| | - Kayo José Garcia de Almeida Castilho Neto
- Department of Pathology, Reproduction and One Health, Faculty of Agrarian and Veterinary Sciences, São Paulo State University (UNESP), Jaboticabal, Sao Paulo, Brazil
| | - Marta M. G. Teixeira
- Department of Parasitology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Sao Paulo, Brazil
| | - Rosangela Zacharias Machado
- Department of Pathology, Reproduction and One Health, Faculty of Agrarian and Veterinary Sciences, São Paulo State University (UNESP), Jaboticabal, Sao Paulo, Brazil
| | - Janine Coombes
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
- School of Pharmacy and Life Sciences, The Robert Gordon University, Aberdeen, United Kingdom
| | - Robin J. Flynn
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
- Waterford Institute of Technology, Waterford, Ireland
| | - Gavin J. Wright
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, United Kingdom
- Department of Biology, Hull York Medical School, York Biomedical Research Institute, University of York, York, United Kingdom
| | - Andrew P. Jackson
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
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Kent RS, Briggs EM, Colon BL, Alvarez C, Silva Pereira S, De Niz M. Paving the Way: Contributions of Big Data to Apicomplexan and Kinetoplastid Research. Front Cell Infect Microbiol 2022; 12:900878. [PMID: 35734575 PMCID: PMC9207352 DOI: 10.3389/fcimb.2022.900878] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/06/2022] [Indexed: 11/13/2022] Open
Abstract
In the age of big data an important question is how to ensure we make the most out of the resources we generate. In this review, we discuss the major methods used in Apicomplexan and Kinetoplastid research to produce big datasets and advance our understanding of Plasmodium, Toxoplasma, Cryptosporidium, Trypanosoma and Leishmania biology. We debate the benefits and limitations of the current technologies, and propose future advancements that may be key to improving our use of these techniques. Finally, we consider the difficulties the field faces when trying to make the most of the abundance of data that has already been, and will continue to be, generated.
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Affiliation(s)
- Robyn S. Kent
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT, United States
| | - Emma M. Briggs
- Institute for Immunology and Infection Research, School of Biological Sciences, University Edinburgh, Edinburgh, United Kingdom
- Wellcome Centre for Integrative Parasitology, Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Beatrice L. Colon
- Wellcome Centre for Anti-Infectives Research, Division of Biological Chemistry and Drug Discovery, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Catalina Alvarez
- de Duve Institute, Université Catholique de Louvain, Brussels, Belgium
| | - Sara Silva Pereira
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - Mariana De Niz
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
- Institut Pasteur, Paris, France
- *Correspondence: Mariana De Niz,
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Salivarian Trypanosomes Have Adopted Intricate Host-Pathogen Interaction Mechanisms That Ensure Survival in Plain Sight of the Adaptive Immune System. Pathogens 2021; 10:pathogens10060679. [PMID: 34072674 PMCID: PMC8229994 DOI: 10.3390/pathogens10060679] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/24/2021] [Accepted: 05/28/2021] [Indexed: 12/21/2022] Open
Abstract
Salivarian trypanosomes are extracellular parasites affecting humans, livestock and game animals. Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense are human infective sub-species of T. brucei causing human African trypanosomiasis (HAT—sleeping sickness). The related T. b. brucei parasite lacks the resistance to survive in human serum, and only inflicts animal infections. Animal trypanosomiasis (AT) is not restricted to Africa, but is present on all continents. T. congolense and T. vivax are the most widespread pathogenic trypanosomes in sub-Saharan Africa. Through mechanical transmission, T. vivax has also been introduced into South America. T. evansi is a unique animal trypanosome that is found in vast territories around the world and can cause atypical human trypanosomiasis (aHT). All salivarian trypanosomes are well adapted to survival inside the host’s immune system. This is not a hostile environment for these parasites, but the place where they thrive. Here we provide an overview of the latest insights into the host-parasite interaction and the unique survival strategies that allow trypanosomes to outsmart the immune system. In addition, we review new developments in treatment and diagnosis as well as the issues that have hampered the development of field-applicable anti-trypanosome vaccines for the implementation of sustainable disease control.
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Nakamura Y, Hayashida K, Delesalle V, Qiu Y, Omori R, Simuunza M, Sugimoto C, Namangala B, Yamagishi J. Genetic Diversity of African Trypanosomes in Tsetse Flies and Cattle From the Kafue Ecosystem. Front Vet Sci 2021; 8:599815. [PMID: 33585616 PMCID: PMC7873289 DOI: 10.3389/fvets.2021.599815] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 01/04/2021] [Indexed: 01/15/2023] Open
Abstract
We clarified the genetic diversity of Trypanosoma spp. within the Kafue ecosystem, using PCR targeting the internal transcribed spacer 1 and the cathepsin L-like cysteine protease (CatL) sequences. The overall prevalence of Trypanosoma spp. in cattle and tsetse flies was 12.65 and 26.85%, respectively. Cattle positive for Trypanosoma vivax had a significantly lower packed cell volume, suggesting that T. vivax is the dominant Trypanosoma spp. causing anemia in this area. Among the 12 operational taxonomic units (OTUs) of T. vivax CatL sequences detected, one was from a known T. vivax lineage, two OTUs were from known T. vivax-like lineages, and nine OTUs were considered novel T. vivax-like lineages. These findings support previous reports that indicated the extensive diversity of T. vivax-like lineages. The findings also indicate that combining CatL PCR with next generation sequencing is useful in assessing Trypanosoma spp. diversity, especially for T. vivax and T. vivax-like lineages. In addition, the 5.42% prevalence of Trypanosoma brucei rhodesiense found in cattle raises concern in the community and requires careful monitoring of human African trypanosomiasis.
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Affiliation(s)
- Yukiko Nakamura
- Graduate School of Infectious Diseases, Hokkaido University, Sapporo, Japan.,Research Center for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Kyoko Hayashida
- Research Center for Zoonosis Control, Hokkaido University, Sapporo, Japan.,International Collaboration Unit, Research Center for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Victoire Delesalle
- Melindika, Non-governmental Organization of International Solidarity, Itezhi-Tezhi, Zambia
| | - Yongjin Qiu
- Research Center for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Ryosuke Omori
- Research Center for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Martin Simuunza
- Department of Disease Control, School of Veterinary Medicine, The University of Zambia, Lusaka, Zambia
| | - Chihiro Sugimoto
- Research Center for Zoonosis Control, Hokkaido University, Sapporo, Japan
| | - Boniface Namangala
- Department of Para-Clinical Studies, School of Veterinary Medicine, The University of Zambia, Lusaka, Zambia
| | - Junya Yamagishi
- Research Center for Zoonosis Control, Hokkaido University, Sapporo, Japan.,International Collaboration Unit, Research Center for Zoonosis Control, Hokkaido University, Sapporo, Japan
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10
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Weber JS, Ngomtcho SCH, Shaida SS, Chechet GD, Gbem TT, Nok JA, Mamman M, Achukwi DM, Kelm S. Genetic diversity of trypanosome species in tsetse flies (Glossina spp.) in Nigeria. Parasit Vectors 2019; 12:481. [PMID: 31610794 PMCID: PMC6792248 DOI: 10.1186/s13071-019-3718-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 09/14/2019] [Indexed: 12/29/2022] Open
Abstract
Background Trypanosomes cause disease in humans and livestock in sub-Saharan Africa and rely on tsetse flies as their main insect vector. Nigeria is the most populous country in Africa; however, only limited information about the occurrence and diversity of trypanosomes circulating in the country is available. Methods Tsetse flies were collected from five different locations in or adjacent to protected areas, i.e. national parks and game reserves, in Nigeria. Proboscis and gut samples were analysed for trypanosome DNA by molecular amplification of the internal transcribed spacer 1 (ITS1) region and part of the trypanosome specific glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) gene. Results The most abundant Trypanosoma species found in the tsetse gut was T. grayi, a trypanosome infecting crocodiles. It was ubiquitously distributed throughout the country, accounting for over 90% of all cases involving trypanosomes. Trypanosoma congolense was detected in gut samples from all locations except Cross River National Park, but not in the proboscis, while T. brucei (sensu lato) was not detected at all. In proboscis samples, T. vivax was the most prominent. The sequence diversity of gGAPDH suggests that T. vivax and T. grayi represent genetically diverse species clusters. This implies that they are highly dynamic populations. Conclusions The prevalence of animal pathogenic trypanosomes throughout Nigeria emphasises the role of protected areas as reservoirs for livestock trypanosomes. The genetic diversity observed within T. vivax and T. grayi populations might be an indication for changing pathogenicity or host range and the origin and consequences of this diversity has to be further investigated.![]()
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Affiliation(s)
- Judith Sophie Weber
- Centre for Biomolecular Interactions, Department of Biology and Chemistry, University of Bremen, Bremen, Germany.
| | - Sen Claudine Henriette Ngomtcho
- Department of Biological Sciences, University of Ngaoundéré, Ngaoundéré, Cameroon.,Ministry of Public Health, Yaoundé, Cameroon
| | | | - Gloria Dada Chechet
- Department of Biochemistry, Ahmadu Bello University, Zaria, Nigeria.,Africa Centre of Excellence for Neglected Tropical Diseases and Forensic Biotechnology, Ahmadu Bello University, Zaria, Nigeria
| | - Thaddeus Terlumun Gbem
- Africa Centre of Excellence for Neglected Tropical Diseases and Forensic Biotechnology, Ahmadu Bello University, Zaria, Nigeria.,Department of Biology, Ahmadu Bello University, Zaria, Nigeria
| | - Jonathan Andrew Nok
- Department of Biochemistry, Ahmadu Bello University, Zaria, Nigeria.,Africa Centre of Excellence for Neglected Tropical Diseases and Forensic Biotechnology, Ahmadu Bello University, Zaria, Nigeria
| | - Mohammed Mamman
- Nigerian Institute for Trypanosomiasis Research, Kaduna, Nigeria.,Africa Centre of Excellence for Neglected Tropical Diseases and Forensic Biotechnology, Ahmadu Bello University, Zaria, Nigeria
| | | | - Sørge Kelm
- Centre for Biomolecular Interactions, Department of Biology and Chemistry, University of Bremen, Bremen, Germany. .,Africa Centre of Excellence for Neglected Tropical Diseases and Forensic Biotechnology, Ahmadu Bello University, Zaria, Nigeria.
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11
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Genetic diversity of trypanosomes pathogenic to livestock in tsetse flies from the Nech Sar National Park in Ethiopia: A concern for tsetse suppressed area in Southern Rift Valley? INFECTION GENETICS AND EVOLUTION 2019; 69:38-47. [DOI: 10.1016/j.meegid.2019.01.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Revised: 01/09/2019] [Accepted: 01/10/2019] [Indexed: 12/20/2022]
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12
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How clonal is Trypanosoma congolense? A necessary clarification of the predominant clonal evolution model. Acta Trop 2019; 190:28-29. [PMID: 30391231 DOI: 10.1016/j.actatropica.2018.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 10/25/2018] [Accepted: 10/27/2018] [Indexed: 11/23/2022]
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13
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Radwanska M, Vereecke N, Deleeuw V, Pinto J, Magez S. Salivarian Trypanosomosis: A Review of Parasites Involved, Their Global Distribution and Their Interaction With the Innate and Adaptive Mammalian Host Immune System. Front Immunol 2018; 9:2253. [PMID: 30333827 PMCID: PMC6175991 DOI: 10.3389/fimmu.2018.02253] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 09/11/2018] [Indexed: 01/27/2023] Open
Abstract
Salivarian trypanosomes are single cell extracellular parasites that cause infections in a wide range of hosts. Most pathogenic infections worldwide are caused by one of four major species of trypanosomes including (i) Trypanosoma brucei and the human infective subspecies T. b. gambiense and T. b. rhodesiense, (ii) Trypanosoma evansi and T. equiperdum, (iii) Trypanosoma congolense and (iv) Trypanosoma vivax. Infections with these parasites are marked by excessive immune dysfunction and immunopathology, both related to prolonged inflammatory host immune responses. Here we review the classification and global distribution of these parasites, highlight the adaptation of human infective trypanosomes that allow them to survive innate defense molecules unique to man, gorilla, and baboon serum and refer to the discovery of sexual reproduction of trypanosomes in the tsetse vector. With respect to the immunology of mammalian host-parasite interactions, the review highlights recent findings with respect to the B cell destruction capacity of trypanosomes and the role of T cells in the governance of infection control. Understanding infection-associated dysfunction and regulation of both these immune compartments is crucial to explain the continued failures of anti-trypanosome vaccine developments as well as the lack of any field-applicable vaccine based anti-trypanosomosis intervention strategy. Finally, the link between infection-associated inflammation and trypanosomosis induced anemia is covered in the context of both livestock and human infections.
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Affiliation(s)
- Magdalena Radwanska
- Laboratory for Biomedical Research, Ghent University Global Campus, Incheon, South Korea
| | - Nick Vereecke
- Laboratory for Biomedical Research, Ghent University Global Campus, Incheon, South Korea.,Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Violette Deleeuw
- Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Joar Pinto
- Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium
| | - Stefan Magez
- Laboratory for Biomedical Research, Ghent University Global Campus, Incheon, South Korea.,Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium
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14
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Van den Broeck F, Tavernier LJM, Vermeiren L, Dujardin JC, Van Den Abbeele J. Mitonuclear genomics challenges the theory of clonality in Trypanosoma congolense: Reply to Tibayrenc and Ayala. Mol Ecol 2018; 27:3425-3431. [PMID: 30142241 DOI: 10.1111/mec.14809] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 07/06/2018] [Accepted: 07/11/2018] [Indexed: 12/11/2022]
Abstract
We recently published the first genomic diversity study of Trypanosoma congolense, a major aetiological agent of Animal African Trypanosomiasis. We demonstrated striking levels of SNP and indel diversity in the Eastern province of Zambia as a consequence of hybridization between divergent trypanosome lineages. We concluded that these and earlier findings in T. congolense challenge the predominant clonal evolution (PCE) model. In a recent comment, Tibayrenc and Ayala claim that there are many features in T. congolense supporting their theory of clonality. While we can follow the reasoning of the authors, we also identify major limitations in their theory and interpretations that resulted in incorrect conclusions. First, we argue that each T. congolense subgroup should be analysed independently as they may represent different (sub)species rather than "near-clades". Second, the authors neglect major findings of two robust population genetic studies on Savannah T. congolense that provide clear evidence of frequent recombination. Third, we reveal additional events of introgressive hybridization in T. congolense by analysing the maxicircle coding region using next-generation sequencing analyses. At last, we pinpoint two important misinterpretations by the authors and show that there are no spatially and temporally widespread clones in T. congolense. We stand by our earlier conclusions that the clonal framework is unlikely to accurately model the population structure of T. congolense. Other theoretical frameworks such as Maynard Smith's epidemic model may better represent the complex ancestry seen in T. congolense, where clones delimited in space and time arise against a background of recombination.
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Affiliation(s)
| | | | - Lieve Vermeiren
- Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
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15
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Silva Pereira S, Casas-Sánchez A, Haines LR, Ogugo M, Absolomon K, Sanders M, Kemp S, Acosta-Serrano Á, Noyes H, Berriman M, Jackson AP. Variant antigen repertoires in Trypanosoma congolense populations and experimental infections can be profiled from deep sequence data using universal protein motifs. Genome Res 2018; 28:1383-1394. [PMID: 30006414 PMCID: PMC6120623 DOI: 10.1101/gr.234146.118] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 07/12/2018] [Indexed: 11/25/2022]
Abstract
African trypanosomes are vector-borne hemoparasites of humans and animals. In the mammal, parasites evade the immune response through antigenic variation. Periodic switching of the variant surface glycoprotein (VSG) coat covering their cell surface allows sequential expansion of serologically distinct parasite clones. Trypanosome genomes contain many hundreds of VSG genes, subject to rapid changes in nucleotide sequence, copy number, and chromosomal position. Thus, analyzing, or even quantifying, VSG diversity over space and time presents an enormous challenge to conventional techniques. Indeed, previous population genomic studies have overlooked this vital aspect of pathogen biology for lack of analytical tools. Here we present a method for analyzing population-scale VSG diversity in Trypanosoma congolense from deep sequencing data. Previously, we suggested that T. congolense VSGs segregate into defined “phylotypes” that do not recombine. In our data set comprising 41 T. congolense genome sequences from across Africa, these phylotypes are universal and exhaustive. Screening sequence contigs with diagnostic protein motifs accurately quantifies relative phylotype frequencies, providing a metric of VSG diversity, called the “variant antigen profile.” We applied our metric to VSG expression in the tsetse fly, showing that certain, rare VSG phylotypes may be preferentially expressed in infective, metacyclic-stage parasites. Hence, variant antigen profiling accurately and rapidly determines the T. congolense VSG gene and transcript repertoire from sequence data, without need for manual curation or highly contiguous sequences. It offers a tractable approach to measuring VSG diversity across strains and during infections, which is imperative to understanding the host–parasite interaction at population and individual scales.
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Affiliation(s)
- Sara Silva Pereira
- Department of Infection Biology, Institute of Infection and Global Health, University of Liverpool, Liverpool L3 5RF, United Kingdom
| | - Aitor Casas-Sánchez
- Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, United Kingdom
| | - Lee R Haines
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, United Kingdom
| | - Moses Ogugo
- International Livestock Research Institute, Nairobi 00100, Kenya
| | - Kihara Absolomon
- International Livestock Research Institute, Nairobi 00100, Kenya
| | - Mandy Sanders
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton CB10 1SA, United Kingdom
| | - Steve Kemp
- International Livestock Research Institute, Nairobi 00100, Kenya
| | - Álvaro Acosta-Serrano
- Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, United Kingdom.,Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, United Kingdom
| | - Harry Noyes
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Matthew Berriman
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton CB10 1SA, United Kingdom
| | - Andrew P Jackson
- Department of Infection Biology, Institute of Infection and Global Health, University of Liverpool, Liverpool L3 5RF, United Kingdom
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16
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Fogue PS, Njiokou F, Simo G. Genetic structure of Trypanosoma congolense "forest type" circulating in domestic animals and tsetse flies in the South-West region of Cameroon. Parasite 2017; 24:51. [PMID: 29261481 PMCID: PMC5737789 DOI: 10.1051/parasite/2017052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 11/12/2017] [Indexed: 11/14/2022] Open
Abstract
Despite the economic impact of trypanosome infections, few investigations have been undertaken on the population genetics and transmission dynamics of animal trypanosomes. In this study, microsatellite markers were used to investigate the population genetics of Trypanosoma congolense “forest type”, with the ultimate goal of understanding its transmission dynamics between tsetse flies and domestic animals. Blood samples were collected from pigs, sheep, goats and dogs in five villages in Fontem, South-West region of Cameroon. In these villages, tsetse were captured, dissected and their mid-guts collected. DNA was extracted from blood and tsetse mid-guts and specific primers were used to identify T. congolense “forest type”. All positive samples were genetically characterized with seven microsatellite markers. Genetic analyses were performed on samples showing single infections of T. congolense “forest type”. Of the 299 blood samples, 137 (46%) were infected by T. congolense “forest type”. About 3% (54/1596) of tsetse fly mid-guts were infected by T. congolense “forest type”. Of 182 samples with T. congolense “forest type”, 52 were excluded from the genetic analysis. The genetic analysis on the 130 remaining samples revealed polymorphism within and between subpopulations of the target trypanosome. The dendrogram of genetic similarities was subdivided into two clusters and three sub-clusters, indicating one major and several minor genotypes of T. congolense “forest type” in tsetse and domestic animals. The low FSTvalues suggest low genetic differentiation and no sub-structuration within subpopulations. The same T. congolense genotypes appear to circulate in tsetse and domestic animals.
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Affiliation(s)
- Pythagore Soubgwi Fogue
- Molecular Parasitology and Entomology Unit, Department of Biochemistry, Faculty of Science, University of Dschang, Dschang, Cameroon
| | - Flobert Njiokou
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé I, Yaoundé, Cameroon
| | - Gustave Simo
- Molecular Parasitology and Entomology Unit, Department of Biochemistry, Faculty of Science, University of Dschang, Dschang, Cameroon
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17
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Tihon E, Imamura H, Dujardin JC, Van Den Abbeele J, Van den Broeck F. Discovery and genomic analyses of hybridization between divergent lineages of Trypanosoma congolense, causative agent of Animal African Trypanosomiasis. Mol Ecol 2017; 26:6524-6538. [PMID: 28752916 DOI: 10.1111/mec.14271] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 05/24/2017] [Accepted: 06/28/2017] [Indexed: 12/19/2022]
Abstract
Hybrid populations and introgressive hybridization remain poorly documented in pathogenic micro-organisms, as such that genetic exchange has been argued to play a minor role in their evolution. Recent work demonstrated the existence of hybrid microsatellite profiles in Trypanosoma congolense, a parasitic protozoan with detrimental effects on livestock productivity in sub-Saharan Africa. Here, we present the first population genomic study of T. congolense, revealing a remarkable number of single nucleotide polymorphisms (SNPs), small insertions/deletions (indels) and gene deletions among 56 parasite genomes from ten African countries. One group of parasites from Zambia was particularly diverse, displaying a substantial number of heterozygous SNP and indel sites compared to T. congolense parasites from the nine other sub-Saharan countries. Genomewide 5-kb phylogenetic analyses based on phased SNP data revealed that these parasites were the product of hybridization between phylogenetically distinct T. congolense lineages. Other parasites within the same region in Zambia presented a mosaic of haplotypic ancestry and genetic variability, indicating that hybrid parasites persisted and recombined beyond the initial hybridization event. Our observations challenge traditional views of trypanosome population biology and encourage future research on the role of hybridization in spreading genes for drug resistance, pathogenicity and virulence.
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Affiliation(s)
- Eliane Tihon
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Hideo Imamura
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Jean-Claude Dujardin
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Jan Van Den Abbeele
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
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18
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Garcia HA, Rodrigues CMF, Rodrigues AC, Pereira DL, Pereira CL, Camargo EP, Hamilton PB, Teixeira MMG. Remarkable richness of trypanosomes in tsetse flies (Glossina morsitans morsitans and Glossina pallidipes) from the Gorongosa National Park and Niassa National Reserve of Mozambique revealed by fluorescent fragment length barcoding (FFLB). INFECTION GENETICS AND EVOLUTION 2017; 63:370-379. [PMID: 28688979 DOI: 10.1016/j.meegid.2017.07.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Revised: 07/03/2017] [Accepted: 07/04/2017] [Indexed: 11/25/2022]
Abstract
Trypanosomes of African wild ungulates transmitted by tsetse flies can cause human and livestock diseases. However, trypanosome diversity in wild tsetse flies remains greatly underestimated. We employed FFLB (fluorescent fragment length barcoding) for surveys of trypanosomes in tsetse flies (3086) from the Gorongosa National Park (GNP) and Niassa National Reserve (NNR) in Mozambique (MZ), identified as Glossina morsitans morsitans (GNP/NNR=77.6%/90.5%) and Glossina pallidipes (22.4%/9.5%). Trypanosomes were microscopically detected in 8.3% of tsetse guts. FFLB of gut samples revealed (GNP/NNR): Trypanosoma congolense of Savannah (27%/63%), Kilifi (16.7%/29.7%) and Forest (1.0%/0.3%) genetic groups; T. simiae Tsavo (36.5%/6.1%); T. simiae (22.2%/17.7%); T. godfreyi (18.2%/7.0%); subgenus Trypanozoon (20.2%/25.7%); T. vivax/T. vivax-like (1.5%/5.2%); T. suis/T. suis-like (9.4%/11.9%). Tsetse proboscises exhibited similar species composition, but most prevalent species were (GNP/NNR): T. simiae (21.9%/28%), T. b. brucei (19.2%/31.7%), and T. vivax/T. vivax-like (19.2%/28.6%). Flies harboring mixtures of trypanosomes were common (~ 64%), and combinations of more than four trypanosomes were especially abundant in the pristine NNR. The non-pathogenic T. theileri was found in 2.5% while FFLB profiles of unknown species were detected in 19% of flies examined. This is the first report on molecular diversity of tsetse flies and their trypanosomes in MZ; all trypanosomes pathogenic for ungulates were detected, but no human pathogens were detected. Overall, two species of tsetse flies harbor 12 species/genotypes of trypanosomes. This notable species richness was likely uncovered because flies were captured in wildlife reserves and surveyed using the method of FFLB able to identify, with high sensitivity and accuracy, known and novel trypanosomes. Our findings importantly improve the knowledge on trypanosome diversity in tsetse flies, revealed the greatest species richness so far reported in tsetse fly of any African country, and indicate the existence of a hidden trypanosome diversity to be discovered in African wildlife protected areas.
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Affiliation(s)
- Herakles A Garcia
- Department of Parasitology, Institute of Biomedical Sciences, University of Sao Paulo, Brazil
| | - Carla M F Rodrigues
- Department of Parasitology, Institute of Biomedical Sciences, University of Sao Paulo, Brazil
| | - Adriana C Rodrigues
- Department of Parasitology, Institute of Biomedical Sciences, University of Sao Paulo, Brazil
| | | | - Carlos L Pereira
- Ministry of Tourism of Mozambique, Wildlife Conservation Society, Mozambique
| | - Erney P Camargo
- Department of Parasitology, Institute of Biomedical Sciences, University of Sao Paulo, Brazil
| | - P B Hamilton
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Marta M G Teixeira
- Department of Parasitology, Institute of Biomedical Sciences, University of Sao Paulo, Brazil.
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19
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Gitonga PK, Ndung'u K, Murilla GA, Thande PC, Wamwiri FN, Auma JE, Ngae GN, Kibugu JK, Kurgat R, Thuita JK. Differential virulence and tsetse fly transmissibility of <i>Trypanosoma congolense</i> and <i>Trypanosoma brucei</i> strains. ACTA ACUST UNITED AC 2017; 84:e1-e10. [PMID: 28697609 PMCID: PMC6238703 DOI: 10.4102/ojvr.v84i1.1412] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 04/26/2017] [Accepted: 04/28/2017] [Indexed: 11/30/2022]
Abstract
African animal trypanosomiasis causes significant economic losses in sub-Saharan African countries because of livestock mortalities and reduced productivity. Trypanosomes, the causative agents, are transmitted by tsetse flies (Glossina spp.). In the current study, we compared and contrasted the virulence characteristics of five Trypanosoma congolense and Trypanosoma brucei isolates using groups of Swiss white mice (n = 6). We further determined the vectorial capacity of Glossina pallidipes, for each of the trypanosome isolates. Results showed that the overall pre-patent (PP) periods were 8.4 ± 0.9 (range, 4–11) and 4.5 ± 0.2 (range, 4–6) for T. congolense and T. brucei isolates, respectively (p < 0.01). Despite the longer mean PP, T. congolense–infected mice exhibited a significantly (p < 0.05) shorter survival time than T. brucei–infected mice, indicating greater virulence. Differences were also noted among the individual isolates with T. congolense KETRI 2909 causing the most acute infection of the entire group with a mean ± standard error survival time of 9 ± 2.1 days. Survival time of infected tsetse flies and the proportion with mature infections at 30 days post-exposure to the infective blood meals varied among isolates, with subacute infection–causing T. congolense EATRO 1829 and chronic infection–causing T. brucei EATRO 2267 isolates showing the highest mature infection rates of 38.5% and 23.1%, respectively. Therefore, our study provides further evidence of occurrence of differences in virulence and transmissibility of eastern African trypanosome strains and has identified two, T. congolense EATRO 1829 and T. brucei EATRO 2267, as suitable for tsetse infectivity and transmissibility experiments.
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Affiliation(s)
| | - Kariuki Ndung'u
- Kenya Agricultural and Livestock Research Organization - Biotechnology Research Institute (KALROBioRI), Kikuyu.
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20
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Gibson W, Kay C, Peacock L. Trypanosoma congolense: Molecular Toolkit and Resources for Studying a Major Livestock Pathogen and Model Trypanosome. ADVANCES IN PARASITOLOGY 2017; 98:283-309. [PMID: 28942771 DOI: 10.1016/bs.apar.2017.03.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The African trypanosomiases are diseases of humans and their livestock caused by trypanosomes carried by bloodsucking tsetse flies. Although the human pathogen Trypanosoma brucei is the best known, other trypanosome species are of greater concern for animal health in sub-Saharan Africa. In particular, Trypanosomacongolense is a major cattle pathogen, which is as amenable to laboratory culture as T. brucei, with the advantage that its whole life cycle can be recapitulated in vitro. Thus, besides being worthy of study in its own right, T. congolense could be useful as a model of trypanosome development. Here we review the biology of T. congolense, highlighting significant and intriguing differences from its sister, T. brucei. An up-to-date compilation of methods for cultivating and genetically manipulating T. congolense in the laboratory is provided, based on published work and current development of methods in our lab, as well as a description of available molecular resources.
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21
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Ponte-Sucre A. An Overview of Trypanosoma brucei Infections: An Intense Host-Parasite Interaction. Front Microbiol 2016; 7:2126. [PMID: 28082973 PMCID: PMC5183608 DOI: 10.3389/fmicb.2016.02126] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Accepted: 12/16/2016] [Indexed: 12/14/2022] Open
Abstract
Trypanosoma brucei rhodesiense and T. brucei gambiense, the causative agents of Human African Trypanosomiasis, are transmitted by tsetse flies. Within the vector, the parasite undergoes through transformations that prepares it to infect the human host. Sequentially these developmental stages are the replicative procyclic (in which the parasite surface is covered by procyclins) and trypo-epimastigote forms, as well as the non-replicative, infective, metacyclic form that develops in the vector salivary glands. As a pre-adaptation to their life in humans, metacyclic parasites begin to express and be densely covered by the Variant Surface Glycoprotein (VSG). Once the metacyclic form invades the human host the parasite develops into the bloodstream form. Herein the VSG triggers a humoral immune response. To avoid this humoral response, and essential for survival while in the bloodstream, the parasite changes its cover periodically and sheds into the surroundings the expressed VSG, thus evading the consequences of the immune system activation. Additionally, tools comparable to quorum sensing are used by the parasite for the successful parasite transmission from human to insect. On the other hand, the human host promotes clearance of the parasite triggering innate and adaptive immune responses and stimulating cytokine and chemokine secretion. All in all, the host–parasite interaction is extremely active and leads to responses that need multiple control sites to develop appropriately.
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Affiliation(s)
- Alicia Ponte-Sucre
- Laboratory of Molecular Physiology, Institute of Experimental Medicine, Luis Razetti School of Medicine, Faculty of Medicine, Universidad Central de Venezuela Caracas, Venezuela
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22
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Tibayrenc M, Ayala FJ. Is Predominant Clonal Evolution a Common Evolutionary Adaptation to Parasitism in Pathogenic Parasitic Protozoa, Fungi, Bacteria, and Viruses? ADVANCES IN PARASITOLOGY 2016; 97:243-325. [PMID: 28325372 DOI: 10.1016/bs.apar.2016.08.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We propose that predominant clonal evolution (PCE) in microbial pathogens be defined as restrained recombination on an evolutionary scale, with genetic exchange scarce enough to not break the prevalent pattern of clonal population structure. The main features of PCE are (1) strong linkage disequilibrium, (2) the widespread occurrence of stable genetic clusters blurred by occasional bouts of genetic exchange ('near-clades'), (3) the existence of a "clonality threshold", beyond which recombination is efficiently countered by PCE, and near-clades irreversibly diverge. We hypothesize that the PCE features are not mainly due to natural selection but also chiefly originate from in-built genetic properties of pathogens. We show that the PCE model obtains even in microbes that have been considered as 'highly recombining', such as Neisseria meningitidis, and that some clonality features are observed even in Plasmodium, which has been long described as panmictic. Lastly, we provide evidence that PCE features are also observed in viruses, taking into account their extremely fast genetic turnover. The PCE model provides a convenient population genetic framework for any kind of micropathogen. It makes it possible to describe convenient units of analysis (clones and near-clades) for all applied studies. Due to PCE features, these units of analysis are stable in space and time, and clearly delimited. The PCE model opens up the possibility of revisiting the problem of species definition in these organisms. We hypothesize that PCE constitutes a major evolutionary strategy for protozoa, fungi, bacteria, and viruses to adapt to parasitism.
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Affiliation(s)
- M Tibayrenc
- Institut de Recherche pour le Développement, Montpellier, France
| | - F J Ayala
- University of California at Irvine, United States
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Messenger LA, Miles MA. Evidence and importance of genetic exchange among field populations of Trypanosoma cruzi. Acta Trop 2015; 151:150-5. [PMID: 26188331 PMCID: PMC4644990 DOI: 10.1016/j.actatropica.2015.05.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 04/25/2015] [Accepted: 05/06/2015] [Indexed: 10/31/2022]
Abstract
Many eukaryotic pathogenic microorganisms that were previously assumed to propagate clonally have retained cryptic sexual cycles. The principal reproductive mode of Trypanosoma cruzi, the aetiological agent of Chagas disease, remains a controversial topic. Despite the existence of two recent natural hybrid lineages, a pervasive view is that recombination has been restrained at an evolutionary scale and is of little epidemiological relevance to contemporary parasite populations. This article reviews the growing number of field studies which indicate that natural hybridization in T. cruzi may be frequent, non-obligatory and idiosyncratic; potentially involving independent exchange of kinetoplast and nuclear genetic material as well as canonical meiotic mechanisms. Together these observations now challenge the traditional paradigm of preponderate clonal evolution in T. cruzi and highlight the need for additional, intensive and appropriately sampled field surveys, complemented by high resolution, combined nuclear and mitochondrial population genetics analyses.
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Koffi M, De Meeûs T, Séré M, Bucheton B, Simo G, Njiokou F, Salim B, Kaboré J, MacLeod A, Camara M, Solano P, Belem AMG, Jamonneau V. Population Genetics and Reproductive Strategies of African Trypanosomes: Revisiting Available Published Data. PLoS Negl Trop Dis 2015; 9:e0003985. [PMID: 26491968 PMCID: PMC4619596 DOI: 10.1371/journal.pntd.0003985] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Trypanosomatidae are a dangerous family of Euglenobionta parasites that threaten the health and economy of millions of people around the world. More precisely describing the population biology and reproductive mode of such pests is not only a matter of pure science, but can also be useful for understanding parasite adaptation, as well as how parasitism, specialization (parasite specificity), and complex life cycles evolve over time. Studying this parasite’s reproductive strategies and population structure can also contribute key information to the understanding of the epidemiology of associated diseases; it can also provide clues for elaborating control programs and predicting the probability of success for control campaigns (such as vaccines and drug therapies), along with emergence or re-emergence risks. Population genetics tools, if appropriately used, can provide precise and useful information in these investigations. In this paper, we revisit recent data collected during population genetics surveys of different Trypanosoma species in sub-Saharan Africa. Reproductive modes and population structure depend not only on the taxon but also on the geographical location and data quality (absence or presence of DNA amplification failures). We conclude on issues regarding future directions of research, in particular vis-à-vis genotyping and sampling strategies, which are still relevant yet, too often, neglected issues.
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Affiliation(s)
- Mathurin Koffi
- Université Jean Lorougnon GUEDE, UFR Environnement-Santé, Laboratoire des Interactions Hôte-Microorganismes-Environnement et Evolution (LIHME), Daloa, Côte d'Ivoire
- * E-mail: (MK); (TDM)
| | - Thierry De Meeûs
- IRD, UMR 177 IRD-CIRAD INTERTRYP, Centre International de Recherche-Développement sur l’Elevage en zone Subhumide (CIRDES), Bobo-Dioulasso, Burkina-Faso
- IRD, UMR177 IRD-CIRAD INTERTRYP, Campus International de Baillarguet, TA A-17/G, Montpellier, France
- * E-mail: (MK); (TDM)
| | - Modou Séré
- IRD, UMR 177 IRD-CIRAD INTERTRYP, Centre International de Recherche-Développement sur l’Elevage en zone Subhumide (CIRDES), Bobo-Dioulasso, Burkina-Faso
| | - Bruno Bucheton
- IRD, UMR177 IRD-CIRAD INTERTRYP, Campus International de Baillarguet, TA A-17/G, Montpellier, France
- Programme National de Lutte contre la Trypanosomiase Humaine Africaine, Conakry, Guinée
| | - Gustave Simo
- University of Dschang, Faculty of Sciences, Department of Biochemistry, Dschang, Cameroon
| | - Flobert Njiokou
- University of Yaoundé 1, Faculty of Sciences, Department of Animal Biology and Physiology, Yaoundé, Cameroon
| | - Bashir Salim
- University of Khartoum, Department of Parasitology, Faculty of Veterinary Medicine, Khartoum North, Sudan
- Parasites, Vectors and Vector-borne Diseases, Agricultural Research Council-Onderstepoort Veterinary Institute, Onderstepoort, South Africa
| | - Jacques Kaboré
- IRD, UMR 177 IRD-CIRAD INTERTRYP, Centre International de Recherche-Développement sur l’Elevage en zone Subhumide (CIRDES), Bobo-Dioulasso, Burkina-Faso
- Université Polytechnique de Bobo-Dioulasso, UFR Sciences et Techniques, Bobo-Dioulasso, Burkina Faso
| | - Annette MacLeod
- University of Glasgow, Wellcome Centre for Molecular Parasitology, Henry Wellcome Building of Comparative Medicine, Glasgow, United Kingdom
| | - Mamadou Camara
- Programme National de Lutte contre la Trypanosomiase Humaine Africaine, Conakry, Guinée
| | - Philippe Solano
- IRD, UMR177 IRD-CIRAD INTERTRYP, Campus International de Baillarguet, TA A-17/G, Montpellier, France
| | - Adrien Marie Gaston Belem
- Université Polytechnique de Bobo-Dioulasso, UFR Sciences et Techniques, Bobo-Dioulasso, Burkina Faso
| | - Vincent Jamonneau
- IRD, UMR 177 IRD-CIRAD INTERTRYP, Centre International de Recherche-Développement sur l’Elevage en zone Subhumide (CIRDES), Bobo-Dioulasso, Burkina-Faso
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PCR and microsatellite analysis of diminazene aceturate resistance of bovine trypanosomes correlated to knowledge, attitude and practice of livestock keepers in South-Western Ethiopia. Acta Trop 2015; 146:45-52. [PMID: 25738729 DOI: 10.1016/j.actatropica.2015.02.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 01/22/2015] [Accepted: 02/23/2015] [Indexed: 11/22/2022]
Abstract
African Animal Trypanosomosis is threatening the agricultural production and cattle breeding more severely than any other livestock disease in the continent, even more since the advent of drug resistance. A longitudinal study was conducted from November 2012 to May 2013 in the Ghibe valley to evaluate diminazene aceturate (DA) resistance and assess livestock owner's perception of trypanocidal drug use. Four Peasant Associations (PAs) were purposively selected and the cattle randomly sampled in each PAs. At the beginning of the study (t0), 106 bovines positive for trypanosomes by the haematocrit centrifugation technique (HCT) and 119 negative control animals were recruited for six months follow-up using HCT, 18S-PCR-RFLP, DpnII-PCR-RFLP and microsatellite analysis. Prevalence of trypanosomosis was 18.1% based on the HCT technique and the mean PCV value was 23.6±5.1% for the 587 sampled cattle. Out of the 106 HCT positive, 64 (60.4%) were positive for the presence of trypanosomes using the 18S-PCR-RFLP. Species detection showed 38 (59.4%) Trypanosoma congolense savannah, 18 (28.1%) Trypanosoma vivax, 5 (7.8%) Trypanosoma theileri and 3 (4.7%) T. congolense Kilifi. Among the T. congolense savannah samples, 31 (81.6%) showed a DA resistant RFLP profile, 2 (5.3%) a mixed profile and 5 did not amplify using the DpnII-PCR-RFLP. A positive HCT had a significant effect on PCV (p<0.001) with the mean PCV value equal to 24.4±0.2% in the absence of trypanosomes and to 20.9±0.3% in the presence of trypanosomes. PCV increased significantly (p<0.001) with 4.4±0.5% one month after treatment. All T. congolense savannah type were analyzed using microsatellite markers TCM1, TCM3 and TCM4. The main events were new infections (40.0%) and relapses (37.5%) with cures lagging at 22.5%. In 10 purposively selected PAs a semi-structured questionnaire was used. The average herd size was the highest in Abelti PA (6.7±1.8 TLU) and the mean herd size was statistically different (p=0.01) in the 10 PAs. Trypanosomosis was designated as the main disease affecting cattle by 97% of the respondents. DA was used by 95.5% of the farmers though more than half of them (51.9%) were not familiar with isometamidium (ISM). There was a trend to overdose young small animals and to underdose large ones. Oxen were treated very frequently (nearly 20 times/year) and calves almost never. To improve the situation in the Ghibe valley, extension messages should be delivered to promote a rational drug use, improved livestock management and the application of strategic vector control methods.
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Simo G, Fogue PS, Melachio TTT, Njiokou F, Kuiate JR, Asonganyi T. Population genetics of forest type of Trypanosoma congolense circulating in Glossina palpalis palpalis of Fontem in the South-West region of Cameroon. Parasit Vectors 2014; 7:385. [PMID: 25142136 PMCID: PMC4261900 DOI: 10.1186/1756-3305-7-385] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 08/08/2014] [Indexed: 11/11/2022] Open
Abstract
Background Genetic variation of microsatellite loci is a widely used method for the analysis of population genetic structure of several organisms. To improve our knowledge on the population genetics of trypanosomes, Trypanosoma congolense forest and savannah types were identified in the mid-guts of Glossina palpalis palpalis caught in five villages of Fontem in the South-West region of Cameroon. From the positive samples of Trypanosoma congolense forest, the genetic diversity and the population genetic structure of these parasites were evaluated. Method For this study, pyramidal traps were set up during three entomological surveys and 3347 tsetse flies were collected, dissected and 1903 midguts collected. DNA was extracted from midguts and specific primers were used to identify Trypanosoma congolense forest and savannah. All Trypanosoma congolense forest positive samples were characterized with seven microsatellite markers. Results Microscopic examination revealed 25 (1.31%) mid-gut infections with trypanosomes while the PCR method identified 120 (6.3%) infections due to Trypanosoma congolense: 94 (78.33%) Trypanosoma congolense forest and 28 (21.77%) Trypanosoma congolense savannah. The trypanosome infection rates varied significantly between villages and years of capture. Menji recorded the highest infection rate (15.11%); and samples captured in 2009 were more infected (14.33%). The microsatellite markers revealed a genetic variability between Trypanosoma congolense forest populations of Fontem villages and 6.38% of mixed infections due to different genotypes of T. congolense “forest type”. Conclusion Our data on the population genetics play in favor of a clonal reproduction of this parasite. The microsatellite markers used here showed a low genetic differentiation and an absence of sub-structuration (FST ≤ 0.0003) between Trypanosoma congolense forest populations of Fontem villages. However, the high FST value (FST ≥ 0.3911) between samples of the Democratic Republic of Congo and those of Fontem villages indicates low migration rates between trypanosomes of these subpopulations. Electronic supplementary material The online version of this article (doi:10.1186/1756-3305-7-385) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gustave Simo
- Molecular Parasitology and Entomology Unit, Department of Biochemistry, Faculty of Science, University of Dschang, Cameroon, PO Box 67, Dschang, Cameroon.
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Séré M, Kaboré J, Jamonneau V, Belem AMG, Ayala FJ, De Meeûs T. Null allele, allelic dropouts or rare sex detection in clonal organisms: simulations and application to real data sets of pathogenic microbes. Parasit Vectors 2014; 7:331. [PMID: 25027508 PMCID: PMC4223633 DOI: 10.1186/1756-3305-7-331] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Accepted: 07/05/2014] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Pathogens and their vectors are organisms whose ecology is often only accessible through population genetics tools based on spatio-temporal variability of molecular markers. However, molecular tools may present technical difficulties due to the masking of some alleles (allelic dropouts and/or null alleles), which tends to bias the estimation of heterozygosity and thus the inferences concerning the breeding system of the organism under study. This is especially critical in clonal organisms in which deviation from panmixia, as measured by Wright's FIS, can, in principle, be used to infer both the extent of clonality and structure in a given population. In particular, null alleles and allelic dropouts are locus specific and likely produce high variance of Wright's FIS across loci, as rare sex is expected to do. In this paper we propose a tool enabling to discriminate between consequences of these technical problems and those of rare sex. METHODS We have performed various simulations of clonal and partially clonal populations. We introduce allelic dropouts and null alleles in clonal data sets and compare the results with those that exhibit increasing rates of sexual recombination. We use the narrow relationship that links Wright's FIS to genetic diversity in purely clonal populations as assessment criterion, since this relationship disappears faster with sexual recombination than with amplification problems of certain alleles. RESULTS We show that the relevance of our criterion for detecting poorly amplified alleles depends partly on the population structure, the level of homoplasy and/or mutation rate. However, the interpretation of data becomes difficult when the number of poorly amplified alleles is above 50%. The application of this method to reinterpret published data sets of pathogenic clonal microbes (yeast and trypanosomes) confirms its usefulness and allows refining previous estimates concerning important pathogenic agents. CONCLUSION Our criterion of superimposing between the FIS expected under clonality and the observed FIS, is effective when amplification difficulties occur in low to moderate frequencies (20-30%).
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Affiliation(s)
- Modou Séré
- Centre International de Recherche-Développement sur l'Elevage en zone Subhumide (CIRDES), 01 BP 454 Bobo-Dioulasso 01, Burkina-Faso.
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Garcia HA, Rodrigues AC, Rodrigues CM, Bengaly Z, Minervino AH, Riet-Correa F, Machado RZ, Paiva F, Batista JS, Neves L, Hamilton PB, Teixeira MM. Microsatellite analysis supports clonal propagation and reduced divergence of Trypanosoma vivax from asymptomatic to fatally infected livestock in South America compared to West Africa. Parasit Vectors 2014; 7:210. [PMID: 24885708 PMCID: PMC4023172 DOI: 10.1186/1756-3305-7-210] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 04/30/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mechanical transmission of the major livestock pathogen Trypanosoma vivax by other biting flies than tsetse allows its spread from Africa to the New World. Genetic studies are restricted to a small number of isolates and based on molecular markers that evolve too slowly to resolve the relationships between American and West African populations and, thus, unable us to uncover the recent history of T. vivax in the New World. METHODS T. vivax genetic diversity, population structure and the source of outbreaks was investigated through the microsatellite multiloci (7 loci) genotype (MLGs) analysis in South America (47isolates from Brazil, Venezuela and French Guiana) and West Africa (12 isolates from The Gambia, Burkina Faso, Ghana, Benin and Nigeria). Relationships among MLGs were explored using phylogenetic, principal component and STRUCTURE analyses. RESULTS Although closely phylogenetically related, for the first time, genetic differences were detected between T. vivax isolates from South America (11 genotypes/47 isolates) and West Africa (12 genotypes/12 isolates) with no MLGs in common. Diversity was far greater across West Africa than in South America, where genotypes from Brazil (MLG1-6), Venezuela (MLG7-10) and French Guiana (MLG11) shared similar but not identical allele composition. No MLG was exclusive to asymptomatic (endemic areas) or sick (outbreaks in non-endemic areas) animals, but only MLGs1, 2 and 3 were responsible for severe haematological and neurological disorders. CONCLUSIONS Our results revealed closely related genotypes of T. vivax in Brazil and Venezuela, regardless of endemicity and clinical conditions of the infected livestock. The MLGs analysis from T. vivax across SA and WA support clonal propagation, and is consistent with the hypothesis that the SA populations examined here derived from common ancestors recently introduced from West Africa. The molecular markers defined here are valuable to assess the genetic diversity, to track the source and dispersion of outbreaks, and to explore the epidemiological and pathological significance of T. vivax genotypes.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Marta Mg Teixeira
- Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brasil.
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Rodrigues AC, Ortiz PA, Costa-Martins AG, Neves L, Garcia HA, Alves JM, Camargo EP, Alfieri SC, Gibson W, Teixeira MM. Congopain genes diverged to become specific to Savannah, Forest and Kilifi subgroups of Trypanosoma congolense, and are valuable for diagnosis, genotyping and phylogenetic inferences. INFECTION GENETICS AND EVOLUTION 2014; 23:20-31. [DOI: 10.1016/j.meegid.2014.01.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 01/10/2014] [Accepted: 01/11/2014] [Indexed: 10/25/2022]
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Population genetics of Trypanosoma brucei rhodesiense: clonality and diversity within and between foci. PLoS Negl Trop Dis 2013; 7:e2526. [PMID: 24244771 PMCID: PMC3828156 DOI: 10.1371/journal.pntd.0002526] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 09/26/2013] [Indexed: 11/19/2022] Open
Abstract
African trypanosomes are unusual among pathogenic protozoa in that they can undergo their complete morphological life cycle in the tsetse fly vector with mating as a non-obligatory part of this development. Trypanosoma brucei rhodesiense, which infects humans and livestock in East and Southern Africa, has classically been described as a host-range variant of the non-human infective Trypanosoma brucei that occurs as stable clonal lineages. We have examined T. b. rhodesiense populations from East (Uganda) and Southern (Malawi) Africa using a panel of microsatellite markers, incorporating both spatial and temporal analyses. Our data demonstrate that Ugandan T. b. rhodesiense existed as clonal populations, with a small number of highly related genotypes and substantial linkage disequilibrium between pairs of loci. However, these populations were not stable as the dominant genotypes changed and the genetic diversity also reduced over time. Thus these populations do not conform to one of the criteria for strict clonality, namely stability of predominant genotypes over time, and our results show that, in a period in the mid 1990s, the previously predominant genotypes were not detected but were replaced by a novel clonal population with limited genetic relationship to the original population present between 1970 and 1990. In contrast, the Malawi T. b. rhodesiense population demonstrated significantly greater diversity and evidence for frequent genetic exchange. Therefore, the population genetics of T. b. rhodesiense is more complex than previously described. This has important implications for the spread of the single copy T. b. rhodesiense gene that allows human infectivity, and therefore the epidemiology of the human disease, as well as suggesting that these parasites represent an important organism to study the influence of optional recombination upon population genetic dynamics. Trypanosomes are single-celled organisms transmitted by the biting tsetse fly, which cause sleeping sickness in humans in sub-Saharan Africa, but also infect livestock and other mammals. Most trypanosomes cannot infect humans as they die in human serum, but two mutants of Trypanosoma brucei have evolved the ability to survive in human serum. This survival in human serum is conferred by the presence of one gene in the East African human-infective T. b. rhodesiense. How often trypanosomes exchange genetic material (they can mate in the tsetse fly) is debated, but will impact upon the spread of genes (e.g. that which confers human infectivity) through a population. We studied T. b. rhodesiense populations from different geographic locations (Malawi and two locations in Uganda), and over time (Uganda), to see if the populations are stable over time and space, using a panel of variable genetic markers enabling assessment of diversity. Our results suggest that there is significant difference in diversity between locations; those in Uganda are very closely related, increasingly so over time, whereas the Malawi population is very genetically diverse, consistent with the trypanosomes mating. These findings suggest that a greater understanding of T. b. rhodesiense population evolution will inform on sleeping sickness epidemiology.
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Nouvellet P, Dumonteil E, Gourbière S. The improbable transmission of Trypanosoma cruzi to human: the missing link in the dynamics and control of Chagas disease. PLoS Negl Trop Dis 2013; 7:e2505. [PMID: 24244766 PMCID: PMC3820721 DOI: 10.1371/journal.pntd.0002505] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 09/16/2013] [Indexed: 01/13/2023] Open
Abstract
Chagas disease has a major impact on human health in Latin America and is becoming of global concern due to international migrations. Trypanosoma cruzi, the etiological agent of the disease, is one of the rare human parasites transmitted by the feces of its vector, as it is unable to reach the salivary gland of the insect. This stercorarian transmission is notoriously poorly understood, despite its crucial role in the ecology and evolution of the pathogen and the disease. The objective of this study was to quantify the probability of T. cruzi vectorial transmission to humans, and to use such an estimate to predict human prevalence from entomological data. We developed several models of T. cruzi transmission to estimate the probability of transmission from vector to host. Using datasets from the literature, we estimated the probability of transmission per contact with an infected triatomine to be 5.8 × 10(-4) (95%CI: [2.6 ; 11.0] × 10(-4)). This estimate was consistent across triatomine species, robust to variations in other parameters, and corresponded to 900-4,000 contacts per case. Our models subsequently allowed predicting human prevalence from vector abundance and infection rate in 7/10 independent datasets covering various triatomine species and epidemiological situations. This low probability of T. cruzi transmission reflected well the complex and unlikely mechanism of transmission via insect feces, and allowed predicting human prevalence from basic entomological data. Although a proof of principle study would now be valuable to validate our models' predictive ability in an even broader range of entomological and ecological settings, our quantitative estimate could allow switching the evaluation of disease risk and vector control program from purely entomological indexes to parasitological measures, as commonly done for other major vector borne diseases. This might lead to different quantitative perspectives as these indexes are well known not to be proportional one to another.
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Affiliation(s)
- Pierre Nouvellet
- Laboratorio de Parasitología, Centro de Investigaciones Regionales "Dr. Hideyo Noguchi", Universidad Autónoma de Yucatán, Mérida, Yucatán, Mexico ; EA 4218 UPVD 'Institut de Modélisation et d'Analyses en Géo-Environnement et Santé', Université de Perpignan Via Domitia, Perpignan, France ; Medical Research Council Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
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Ramírez JD, Tapia-Calle G, Guhl F. Genetic structure of Trypanosoma cruzi in Colombia revealed by a High-throughput Nuclear Multilocus Sequence Typing (nMLST) approach. BMC Genet 2013; 14:96. [PMID: 24079755 PMCID: PMC3850472 DOI: 10.1186/1471-2156-14-96] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 09/25/2013] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Chagas disease is a systemic pathology caused by Trypanosoma cruzi. This parasite reveals remarkable genetic variability, evinced in six Discrete Typing Units (DTUs) named from T. cruzi I to T. cruzi VI (TcI to TcVI). Recently newly identified genotypes have emerged such as TcBat in Brazil, Colombia and Panama associated to anthropogenic bats. The genotype with the broadest geographical distribution is TcI, which has recently been associated to severe cardiomyopathies in Argentina and Colombia. Therefore, new studies unraveling the genetic structure and natural history of this DTU must be pursued. RESULTS We conducted a spatial and temporal analysis on 50 biological clones of T. cruzi I (TcI) isolated from humans with different clinical phenotypes, triatomine bugs and mammal reservoirs across three endemic regions for Chagas disease in Colombia. These clones were submitted to a nuclear Multilocus Sequence Typing (nMLST) analysis in order to elucidate its genetic diversity and clustering. After analyzing 13 nuclear housekeeping genes and obtaining a 5821 bp length alignment, we detected two robust genotypes within TcI henceforth named TcIDOM (associated to human infections) and a second cluster associated to peridomestic and sylvatic populations. Additionaly, we detected putative events of recombination and an intriguing lack of linkage disequilibrium. CONCLUSIONS These findings reinforce the emergence of an enigmatic domestic T. cruzi genotype (TcIDOM), and demonstrates the high frequency of recombination at nuclear level across natural populations of T. cruzi. Therefore, the need to pursue studies focused on the diferential virulence profiles of TcI strains. The biological and epidemiological implications of these findings are herein discussed.
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Affiliation(s)
- Juan David Ramírez
- Centro de Investigaciones en Microbiología y Parasitología Tropical (CIMPAT), Universidad de Los Andes, Bogotá, Colombia.
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Rotureau B, Van Den Abbeele J. Through the dark continent: African trypanosome development in the tsetse fly. Front Cell Infect Microbiol 2013; 3:53. [PMID: 24066283 PMCID: PMC3776139 DOI: 10.3389/fcimb.2013.00053] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 08/29/2013] [Indexed: 11/13/2022] Open
Abstract
African trypanosomes are unicellular flagellated parasites causing trypanosomiases in Africa, a group of severe diseases also known as sleeping sickness in human and nagana in cattle. These parasites are almost exclusively transmitted by the bite of the tsetse fly. In this review, we describe and compare the three developmental programs of the main trypanosome species impacting human and animal health, with focus on the most recent observations. From here, some reflections are made on research issues concerning trypanosome developmental biology in the tsetse fly that are to be addressed in the future.
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Affiliation(s)
- Brice Rotureau
- Trypanosome Cell Biology Unit, Institut Pasteur and CNRS URA 2581, Paris, France.
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How clonal are Trypanosoma and Leishmania? Trends Parasitol 2013; 29:264-9. [DOI: 10.1016/j.pt.2013.03.007] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 03/12/2013] [Accepted: 03/13/2013] [Indexed: 11/20/2022]
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Simo G, Sobgwi PF, Njitchouang GR, Njiokou F, Kuiate JR, Cuny G, Asonganyi T. Identification and genetic characterization of Trypanosoma congolense in domestic animals of Fontem in the South-West region of Cameroon. INFECTION GENETICS AND EVOLUTION 2013; 18:66-73. [PMID: 23624186 DOI: 10.1016/j.meegid.2013.04.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 03/30/2013] [Accepted: 04/16/2013] [Indexed: 10/26/2022]
Abstract
To understand the circulation and the spread of Trypanosoma congolense genotypes in animals of Fontem in the southwest region of Cameroon, T. congolense forest and T. congolense savannah were investigated in 397 domestic animals in eight villages. Out of the 397 domestic animals, 86 (21.7%) were found infected by trypanosomes, using the capillary tube centrifugation test. The PCR with specific primers identified 163 (41.1%) and 81 (20.4%) animals infected by T. congolense forest and T. congolense savannah, respectively; showing for the first time the circulation of T. congolense savannah in the Fontem region. No infection with T. congolense savannah was found in pigs whereas goats and sheep were infected by T. congolense forest and/or T. congolense savannah. The prevalence of trypanosomes varied significantly amongst villages and animal species. The genotyping of T. congolense forest positive samples using microsatellites markers showed that multiple genotypes occurred in 27.2% (44/163) of animals sampled, whereas single genotypes were found in 73.8% (119/163) of samples. Some alleles were found in all animal species as well as in all villages and were responsible for major genotypes, whereas others (rare alleles) were identified only in some animals of few villages. These rare alleles were characteristic of specific genotypes, assimilated to minor genotypes which can be spread in the region through tsetse flies. The microsatellite markers show a low genetic variability and an absence of sub-structuration within T. congolense forest. The analysis of the microsatellite data revealed a predominant clonal reproduction within T. congolense forest. Pigs were the animal species with the highest number of different genotypes of T. congolense forest. They seem to play an important epidemiological role in the propagation and spread of different genotypes of T. congolense.
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Affiliation(s)
- Gustave Simo
- Department of Biochemistry, Faculty of Science, University of Dschang, Cameroon.
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Tibayrenc M, Ayala FJ. Reproductive clonality of pathogens: a perspective on pathogenic viruses, bacteria, fungi, and parasitic protozoa. Proc Natl Acad Sci U S A 2012; 109:E3305-13. [PMID: 22949662 PMCID: PMC3511763 DOI: 10.1073/pnas.1212452109] [Citation(s) in RCA: 146] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We propose that clonal evolution in micropathogens be defined as restrained recombination on an evolutionary scale, with genetic exchange scarce enough to not break the prevalent pattern of clonal population structure, a definition already widely used for all kinds of pathogens, although not clearly formulated by many scientists and rejected by others. The two main manifestations of clonal evolution are strong linkage disequilibrium (LD) and widespread genetic clustering ("near-clading"). We hypothesize that this pattern is not mainly due to natural selection, but originates chiefly from in-built genetic properties of pathogens, which could be ancestral and could function as alternative allelic systems to recombination genes ("clonality/sexuality machinery") to escape recombinational load. The clonal framework of species of pathogens should be ascertained before any analysis of biomedical phenotypes (phylogenetic character mapping). In our opinion, this model provides a conceptual framework for the population genetics of any micropathogen.
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Affiliation(s)
- Michel Tibayrenc
- Maladies Infectieuses et Vecteurs Ecologie, Génétique, Evolution et Contrôle, Institut de Rercherche pour le Développement 224, Centre National de la Recherche Scientifique 5290, Universités Montpellier 1 and 2, 34394 Montpellier Cedex 5, France; and
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697
| | - Francisco J. Ayala
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697
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Simo G, Njitchouang GR, Njiokou F, Cuny G, Asonganyi T. Genetic characterization of Trypanosoma brucei circulating in domestic animals of the Fontem sleeping sickness of Cameroon. Microbes Infect 2012; 14:651-8. [DOI: 10.1016/j.micinf.2012.02.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Revised: 02/09/2012] [Accepted: 02/10/2012] [Indexed: 11/26/2022]
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References. Parasitology 2012. [DOI: 10.1002/9781119968986.refs] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Antigenic diversity is generated by distinct evolutionary mechanisms in African trypanosome species. Proc Natl Acad Sci U S A 2012; 109:3416-21. [PMID: 22331916 DOI: 10.1073/pnas.1117313109] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Antigenic variation enables pathogens to avoid the host immune response by continual switching of surface proteins. The protozoan blood parasite Trypanosoma brucei causes human African trypanosomiasis ("sleeping sickness") across sub-Saharan Africa and is a model system for antigenic variation, surviving by periodically replacing a monolayer of variant surface glycoproteins (VSG) that covers its cell surface. We compared the genome of Trypanosoma brucei with two closely related parasites Trypanosoma congolense and Trypanosoma vivax, to reveal how the variant antigen repertoire has evolved and how it might affect contemporary antigenic diversity. We reconstruct VSG diversification showing that Trypanosoma congolense uses variant antigens derived from multiple ancestral VSG lineages, whereas in Trypanosoma brucei VSG have recent origins, and ancestral gene lineages have been repeatedly co-opted to novel functions. These historical differences are reflected in fundamental differences between species in the scale and mechanism of recombination. Using phylogenetic incompatibility as a metric for genetic exchange, we show that the frequency of recombination is comparable between Trypanosoma congolense and Trypanosoma brucei but is much lower in Trypanosoma vivax. Furthermore, in showing that the C-terminal domain of Trypanosoma brucei VSG plays a crucial role in facilitating exchange, we reveal substantial species differences in the mechanism of VSG diversification. Our results demonstrate how past VSG evolution indirectly determines the ability of contemporary parasites to generate novel variant antigens through recombination and suggest that the current model for antigenic variation in Trypanosoma brucei is only one means by which these parasites maintain chronic infections.
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McInnes LM, Dargantes AP, Ryan UM, Reid SA. Microsatellite typing and population structuring of Trypanosoma evansi in Mindanao, Philippines. Vet Parasitol 2011; 187:129-39. [PMID: 22230026 DOI: 10.1016/j.vetpar.2011.12.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2011] [Revised: 12/03/2011] [Accepted: 12/13/2011] [Indexed: 10/14/2022]
Abstract
Trypanosoma evansi, a blood-borne protozoan parasite with an extensive geographical range is the causative agent of the livestock disease known as surra. A total of 140 out of 179 T. evansi isolates collected between 2006 and 2007 from 44 villages (comprising of 16 reported surra outbreaks) in 3 provinces (Agusan del Sur (ADS), Surigao del Sur (SDS) and Agusan del Norte (ADN)) in Mindanao, Philippines were each successfully genotyped using a suite of 7 polymorphic microsatellites. The study identified 16 multi locus genotypes (MLG) within the T. evansi isolates and evidence of the spread of surra outbreaks from one village to another, most likely due to the movement of infected animals. Genotyping provided evidence of population sub-structuring with 3 populations (I, II and III (only 1 isolate)) identified. The most abundant population was II, which was the predominant population in ADS and SDS (p=0.022). In addition, buffalo mortality was statistically higher in outbreak areas associated with isolates from population I (13.6%) than with isolates from population II (6.9%) (p=0.047). The present study has highlighted the utility of microsatellite loci to improve understanding of the epidemiology of T. evansi and in tracking surra outbreaks.
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Affiliation(s)
- L M McInnes
- Division of Health Sciences, School of Veterinary and Biomedical Sciences, Murdoch University, Murdoch, Perth, WA 6150, Australia.
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Abstract
Trypanosomes are protozoan parasites of medical and veterinary importance. It is well established that different species, subspecies and strains of trypanosome can cause very different disease in the mammalian host, exemplified by the two human-infective subspecies of Trypanosoma brucei that cause either acute or chronic disease. We are beginning to understand how the host response shapes the course of the disease and how genetic variation in the host can be a factor in disease severity, particularly in the mouse model, but until recently the role of parasite genetic variation that determines differential disease outcome has been a neglected area. This review will discuss the recent advances in this field, covering both our current knowledge of the T. brucei genes involved and the approaches that are leading towards the identification of T. brucei virulence genes. Finally, the potential for using parasite genotype variation to examine the evolutionary context of virulence will be discussed.
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Affiliation(s)
- L J Morrison
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
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Van den Bossche P, Delespaux V. Options for the control of tsetse-transmitted livestock trypanosomosis. An epidemiological perspective. Vet Parasitol 2011; 181:37-42. [DOI: 10.1016/j.vetpar.2011.04.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Tait A, Morrison LJ, Duffy CW, Cooper A, Turner CMR, Macleod A. Trypanosome genetics: populations, phenotypes and diversity. Vet Parasitol 2011; 181:61-8. [PMID: 21570772 DOI: 10.1016/j.vetpar.2011.04.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In the last decade, there has been a wide range of studies using a series of molecular markers to investigate the genotypic diversity of some of the important species of African trypanosomes. Here, we review this work and provide an update of our current understanding of the mechanisms that generate this diversity based on population genetic analysis. In parallel with field based studies, our knowledge of the key features of the system of genetic exchange in Trypanosoma brucei, based on laboratory analysis, has reached the point at which this system can be used as a tool to determine the genetic basis of a phenotype. In this context, we have outlined our current knowledge of the basis for phenotypic variation among strains of trypanosomes, and highlight that this is a relatively under researched area, except for work on drug resistance. There is clear evidence for 'strain'-specific variation in tsetse transmission, a range of virulence/pathogenesis phenotypes and the ability to cross the blood brain barrier. The potential for using genetic analysis to dissect these phenotypes is illustrated by the recent work defining a locus determining organomegaly for T. brucei. When these results are considered in relation to the body of research on the variability of the host response to infection, it is clear that there is a need to integrate the study of host and parasite diversity in relation to understanding infection outcome.
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Affiliation(s)
- Andy Tait
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, United Kingdom.
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Thompson PC, Rosenthal BM, Hare MP. An evolutionary legacy of sex and clonal reproduction in the protistan oyster parasite Perkinsus marinus. INFECTION GENETICS AND EVOLUTION 2011; 11:598-609. [DOI: 10.1016/j.meegid.2011.01.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 01/12/2011] [Accepted: 01/13/2011] [Indexed: 11/24/2022]
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Simo G, Njitchouang GR, Njiokou F, Cuny G, Asonganyi T. Trypanosoma brucei s.l.: Microsatellite markers revealed high level of multiple genotypes in the mid-guts of wild tsetse flies of the Fontem sleeping sickness focus of Cameroon. Exp Parasitol 2011; 128:272-8. [PMID: 21376044 DOI: 10.1016/j.exppara.2011.02.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 10/25/2010] [Accepted: 02/21/2011] [Indexed: 11/27/2022]
Abstract
To identify Trypanosoma brucei genotypes which are potentially transmitted in a sleeping sickness focus, microsatellite markers were used to characterize T. brucei found in the mid-guts of wild tsetse flies of the Fontem sleeping sickness focus in Cameroon. For this study, two entomological surveys were performed during which 2685 tsetse flies were collected and 1596 (59.2%) were dissected. Microscopic examination revealed 1.19% (19/1596) mid-gut infections with trypanosomes; the PCR method identified 4.7% (75/1596) infections with T. brucei in the mid-guts. Of these 75 trypanosomes identified in the mid-guts, Trypanosoma brucei gambiense represented 0.81% (13/1596) of them, confirming the circulation of human infective parasite in the Fontem focus. Genetic characterization of the 75 T. brucei samples using five microsatellite markers revealed not only multiple T. brucei genotypes (47%), but also single genotypes (53%) in the mid-guts of the wild tsetse flies. These results show that there is a wide range of trypanosome genotypes circulating in the mid-guts of wild tsetse flies from the Fontem sleeping sickness focus. They open new avenues to undertake investigations on the maturation of multiple infections observed in the tsetse fly mid-guts. Such investigations may allow to understand how the multiple infections evolve from the tsetse flies mid-guts to the salivary glands and also to understand the consequence of these evolutions on the dynamic (which genotype is transmitted to mammals) of trypanosomes transmission.
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Affiliation(s)
- Gustave Simo
- Department of Biochemistry, Faculty of Science, P.O. Box 67, University of Dschang, Dschang, Cameroon.
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Extraordinary Trypanosoma cruzi diversity within single mammalian reservoir hosts implies a mechanism of diversifying selection. Int J Parasitol 2011; 41:609-14. [PMID: 21232539 PMCID: PMC3084450 DOI: 10.1016/j.ijpara.2010.12.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Revised: 12/13/2010] [Accepted: 12/14/2010] [Indexed: 11/21/2022]
Abstract
Trypanosoma cruzi is an evolutionarily ancient parasitic protozoan endemic to the Americas. Multiple genetic and phenotypic markers indicate that this parasite is highly diverse, with several divergent and discrete major genotypes reported. Infection multiclonality has been observed among numerous metazoan and unicellular endoparasitic species. However, few studies report the complexity of mixed infections within an individual host in any detail or consider their ecological and biological implications. Here we report extraordinary genetic diversity within single reservoir hosts of T. cruzi I using nine polymorphic microsatellite markers across 211 clones from eight mammals from three different sylvatic foci in South America. Forty-nine distinct multilocus genotypes were defined, with as many as 10 isolated from the same host. We discuss our data in the light of previous population genetic studies of this and related parasitic protozoa and contrast high levels of diversity within each host with the precarious nature of T. cruzi contaminative vectorial transmission. Finally, we propose that non-neutral processes could easily account for the diversity we observe and suggest a functional link with survival in the host.
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Ocaña-Mayorga S, Llewellyn MS, Costales JA, Miles MA, Grijalva MJ. Sex, subdivision, and domestic dispersal of Trypanosoma cruzi lineage I in southern Ecuador. PLoS Negl Trop Dis 2010; 4:e915. [PMID: 21179502 PMCID: PMC3001902 DOI: 10.1371/journal.pntd.0000915] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 11/15/2010] [Indexed: 11/25/2022] Open
Abstract
Background Molecular epidemiology at the community level has an important guiding role in zoonotic disease control programmes where genetic markers are suitably variable to unravel the dynamics of local transmission. We evaluated the molecular diversity of Trypanosoma cruzi, the etiological agent of Chagas disease, in southern Ecuador (Loja Province). This kinetoplastid parasite has traditionally been a paradigm for clonal population structure in pathogenic organisms. However, the presence of naturally occurring hybrids, mitochondrial introgression, and evidence of genetic exchange in the laboratory question this dogma. Methodology/Principal Findings Eighty-one parasite isolates from domiciliary, peridomiciliary, and sylvatic triatomines and mammals were genotyped across 10 variable microsatellite loci. Two discrete parasite populations were defined: one predominantly composed of isolates from domestic and peridomestic foci, and another predominantly composed of isolates from sylvatic foci. Spatial genetic variation was absent from the former, suggesting rapid parasite dispersal across our study area. Furthermore, linkage equilibrium between loci, Hardy-Weinberg allele frequencies at individual loci, and a lack of repeated genotypes are indicative of frequent genetic exchange among individuals in the domestic/peridomestic population. Conclusions/Significance These data represent novel population-level evidence of an extant capacity for sex among natural cycles of T. cruzi transmission. As such they have dramatic implications for our understanding of the fundamental genetics of this parasite. Our data also elucidate local disease transmission, whereby passive anthropogenic domestic mammal and triatomine dispersal across our study area is likely to account for the rapid domestic/peridomestic spread of the parasite. Finally we discuss how this, and the observed subdivision between sympatric sylvatic and domestic/peridomestic foci, can inform efforts at Chagas disease control in Ecuador. Trypanosoma cruzi is transmitted by blood sucking insects known as triatomines. This protozoan parasite commonly infects wild and domestic mammals in South and Central America. However, triatomines also transmit the parasite to people, and human infection with T. cruzi is known as Chagas disease, a major public health concern in Latin America. Understanding the complex dynamics of parasite spread between wild and domestic environments is essential to design effective control measures to prevent the spread of Chagas disease. Here we describe T. cruzi genetic diversity and population dynamics in southern Ecuador. Our findings indicate that the parasite circulates in two largely independent cycles: one corresponding to the sylvatic environment and one related to the domestic/peridomestic environment. Furthermore, our data indicate that human activity might promote parasite dispersal among communties. This information is the key for the design of control programmes in Southern Ecuador. Finally, we have encountered evidence of a sexual reproductive mode in the domestic T. cruzi population, which constitutes a new and intriguing finding with regards to the biology of this parasite.
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Affiliation(s)
- Sofía Ocaña-Mayorga
- Centro de Investigación en Enfermedades Infecciosas, Pontificia Universidad Católica del Ecuador, Quito, Ecuador
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Inference of population structure of Leishmania donovani strains isolated from different Ethiopian visceral leishmaniasis endemic areas. PLoS Negl Trop Dis 2010; 4:e889. [PMID: 21103373 PMCID: PMC2982834 DOI: 10.1371/journal.pntd.0000889] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Accepted: 10/21/2010] [Indexed: 11/28/2022] Open
Abstract
Background Parasites' evolution in response to parasite-targeted control strategies, such as vaccines and drugs, is known to be influenced by their population genetic structure. The aim of this study was to describe the population structure of Ethiopian strains of Leishmania donovani derived from different areas endemic for visceral leishmaniasis (VL) as a prerequisite for the design of effective control strategies against the disease. Methodology/Principal Findings Sixty-three strains of L. donovani newly isolated from VL cases in the two main Ethiopian foci, in the north Ethiopia (NE) and south Ethiopia (SE) of the country were investigated by using 14 highly polymorphic microsatellite markers. The microsatellite profiles of 60 previously analysed L. donovani strains from Sudan, Kenya and India were included for comparison. Multilocus microsatellite typing placed strains from SE and Kenya (n = 30) in one population and strains from NE and Sudan (n = 65) in another. These two East African populations corresponded to the areas of distribution of two different sand fly vectors. In NE and Sudan Phlebotomus orientalis has been implicated to transmit the parasites and in SE and Kenya P. martini. The genetic differences between parasites from NE and SE are also congruent with some phenotypic differences. Each of these populations was further divided into two subpopulations. Interestingly, in one of the subpopulations of the population NE we observed predominance of strains isolated from HIV-VL co-infected patients and of strains with putative hybrid genotypes. Furthermore, high inbreeding irreconcilable from strict clonal reproduction was found for strains from SE and Kenya indicating a mixed-mating system. Conclusions/Significance This study identified a hierarchical population structure of L. donovani in East Africa. The existence of two main, genetically and geographically separated, populations could reflect different parasite-vector associations, different ecologies and varying host backgrounds and should be further investigated. In the Horn of Africa, visceral leishmaniasis, caused by protozoan parasites of the Leishmania donovani complex, continues to pose a major health problem affecting the poorest of the poor. Population genetic studies are crucial for the development of drugs and vaccines against microorganisms. However, our knowledge about the population structure of L. donovani parasites in this region is still very limited. Using a highly discriminatory multilocus microsatellite typing approach, we found a remarkably high genetic diversity among the East African strains of L. donovani studied which grouped into two genetically and geographically distinct populations comprising parasites from SE and Kenya, and those from NE and Sudan. Despite Leishmania being widely regarded as a clonal organism, our results suggest a possible co-existence of clonal and sexually reproducing strains of L. donovani from SE. The information obtained by the present study is helpful for future design of parasite-targeted control measures in East Africa.
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Abstract
Sexual reproduction enables eukaryotic organisms to reassort genetic diversity and purge deleterious mutations, producing better-fit progeny. Sex arose early and pervades eukaryotes. Fungal and parasite pathogens once thought asexual have maintained cryptic sexual cycles, including unisexual or parasexual reproduction. As pathogens become niche and host adapted, sex appears to specialize to promote inbreeding and clonality yet maintain outcrossing potential. During self-fertile sexual modes, sex itself may generate genetic diversity de novo. Mating-type loci govern fungal sexual identity; how parasites establish sexual identity is unknown. Comparing and contrasting fungal and parasite sex promises to reveal how microbial pathogens evolved and are evolving.
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Affiliation(s)
- Joseph Heitman
- Department of Molecular Genetics and Microbiology, Center for Microbial Pathogenesis, Duke University Medical Center, Durham, NC 27710, USA.
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Holzmuller P, Herder S, Cuny G, De Meeûs T. From clonal to sexual: a step in T. congolense evolution? Trends Parasitol 2009; 26:56-60. [PMID: 20006549 DOI: 10.1016/j.pt.2009.11.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Revised: 11/02/2009] [Accepted: 11/19/2009] [Indexed: 10/20/2022]
Abstract
Although clearly demonstrated in Trypanosoma brucei, genetic exchange remains controversial in other trypanosome species. Recently, Morrison and co-workers applied a population-genetics analysis, and established the existence of mating in Trypanosoma congolense. Starting from this original discovery, we focus here on the important question of how mating is induced during the trypanosome life cycle and discuss the use of statistics to evidence this type of non-obligatory biological process.
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Affiliation(s)
- Philippe Holzmuller
- CIRAD UMR 17 Trypanosomes, TA A-17/G, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France.
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