1
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Araújo BL, Adriano EA, Franzolin GN, Zatti SA, Naldoni J. A novel Ceratomyxa species (Myxozoa: Cnidaria) infecting an Amazonian catfish. Parasitol Int 2022; 89:102582. [PMID: 35395395 DOI: 10.1016/j.parint.2022.102582] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/31/2022] [Accepted: 03/31/2022] [Indexed: 11/26/2022]
Abstract
Parasites are important organisms for the health of ecosystems. While the Amazon Basin is home to a great diversity of ichthyofauna, our knowledge of myxozoan diversity in the biome remains relatively limited. The present study describes a new myxozoan species, Ceratomyxa mandii n. sp., parasitizing the gallbladder of the Amazonian catfish Pimelodina flavipinnis (Pimelodidae) from the Solimões River, in the region of Manaus, Brazil. Light and electron microscopy, small subunit ribosomal DNA (SSU rDNA) sequencing and phylogenetic analysis were performed. The new species exhibited worm-like plasmodia with undulatory motility. The SSU rDNA based phylogenetic analysis revealed it to be a sister taxon of C. gracillima, which also parasitizes an Amazonian pimelodid fish, possibly reflecting a host-parasite co-speciation process. This study contributes to our understanding of this little sampled group of organisms.
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Affiliation(s)
- Bruno L Araújo
- Department of Ecology and Evolutionary Biology, Federal University of São Paulo, Diadema, SP, Brazil
| | - Edson A Adriano
- Department of Ecology and Evolutionary Biology, Federal University of São Paulo, Diadema, SP, Brazil; Department of Animal Biology, Institute of Biology, State University of Campinas - UNICAMP, Campinas, SP, Brazil.
| | - Gustavo N Franzolin
- Department of Ecology and Evolutionary Biology, Federal University of São Paulo, Diadema, SP, Brazil
| | - Suellen A Zatti
- Department of Veterinary Medicine, School of Animal Husbandry and Food Engineering, São Paulo University - FZEA/USP, Pirassununga, SP, Brazil
| | - Juliana Naldoni
- Department of Ecology and Evolutionary Biology, Federal University of São Paulo, Diadema, SP, Brazil
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2
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Bass D, Del Campo J. Microeukaryotes in animal and plant microbiomes: Ecologies of disease? Eur J Protistol 2020; 76:125719. [PMID: 32736314 DOI: 10.1016/j.ejop.2020.125719] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 04/28/2020] [Accepted: 05/25/2020] [Indexed: 02/06/2023]
Abstract
Studies of animal and plant microbiomes are burgeoning, but the majority of these focus on bacteria and rarely include microeukaryotes other than fungi. However, there is growing evidence that microeukaryotes living on and in larger organisms (e.g. plants, animals, macroalgae) are diverse and in many cases abundant. We present here a new combination of 'anti-metazoan' primers: 574*f-UNonMet_DB that amplify a wide diversity of microeukaryotes including some groups that are difficult to amplify using other primer combinations. While many groups of microeukaryotic parasites are recognised, myriad other microeukaryotes are associated with hosts as previously unknown parasites (often genetically divergent so difficult to amplify using standard PCR primers), opportunistic parasites, commensals, and other ecto- and endo-symbionts, across the 'symbiotic continuum'. These fulfil a wide range of roles from pathogenesis to mutually beneficial symbioses, but mostly their roles are unknown and likely fall somewhere along this spectrum, with the potential to switch the nature of their interactions with the host under different conditions. The composition and dynamics of host-associated microbial communities are also increasingly recognised as important moderators of host health. This 'pathobiome' approach to understanding disease is beginning to supercede a one-pathogen-one-disease paradigm, which cannot sufficiently explain many disease scenarios.
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Affiliation(s)
- David Bass
- Centre for Environment, Aquaculture and Fisheries Science (Cefas), Barrack Road, Weymouth, Dorset DT4 8UB, UK; Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK; Sustainable Aquaculture Futures, University of Exeter, Exeter EX4 4QD, UK; Biosciences, University of Exeter, Stocker Road, Exeter EX4 4HB, UK.
| | - Javier Del Campo
- Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA
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3
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Bass D, Stentiford GD, Wang HC, Koskella B, Tyler CR. The Pathobiome in Animal and Plant Diseases. Trends Ecol Evol 2019; 34:996-1008. [PMID: 31522755 DOI: 10.1016/j.tree.2019.07.012] [Citation(s) in RCA: 126] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 07/14/2019] [Accepted: 07/23/2019] [Indexed: 12/11/2022]
Abstract
A growing awareness of the diversity and ubiquity of microbes (eukaryotes, prokaryotes, and viruses) associated with larger 'host' organisms has led to the realisation that many diseases thought to be caused by one primary agent are the result of interactions between multiple taxa and the host. Even where a primary agent can be identified, its effect is often moderated by other symbionts. Therefore, the one pathogen-one disease paradigm is shifting towards the pathobiome concept, integrating the interaction of multiple symbionts, host, and environment in a new understanding of disease aetiology. Taxonomically, pathobiomes are variable across host species, ecology, tissue type, and time. Therefore, a more functionally driven understanding of pathobiotic systems is necessary, based on gene expression, metabolic interactions, and ecological processes.
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Affiliation(s)
- David Bass
- Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Barrack Road, The Nothe, Weymouth, DT4 8UB, UK; Sustainable Aquaculture Futures, University of Exeter, Exeter, EX4 4QD, UK; Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK.
| | - Grant D Stentiford
- Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Barrack Road, The Nothe, Weymouth, DT4 8UB, UK; Sustainable Aquaculture Futures, University of Exeter, Exeter, EX4 4QD, UK
| | - Han-Ching Wang
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, 70101, Taiwan; International Center for Scientific Development of Shrimp Aquaculture, National Cheng Kung University, Tainan, 70101, Taiwan
| | - Britt Koskella
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Charles R Tyler
- Sustainable Aquaculture Futures, University of Exeter, Exeter, EX4 4QD, UK; Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4HB, UK
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4
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Okamura B, Hartigan A, Naldoni J. Extensive Uncharted Biodiversity: The Parasite Dimension. Integr Comp Biol 2019; 58:1132-1145. [PMID: 29860443 DOI: 10.1093/icb/icy039] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Parasites are often hidden in their hosts and exhibit patchy spatial distributions. This makes them relatively difficult to detect and sample. Consequently we have poor knowledge of parasite diversities, distributions, and extinction. We evaluate our general understanding of parasite diversity and highlight the enormous bias in research on parasites such as helminths and arthropods that infect vertebrate hosts. We then focus on Myxozoa as an exemplary case for demonstrating uncharted parasite diversity. Myxozoans are a poorly recognized but speciose clade of endoparasitic cnidarians with complex life cycles that have radiated to exploit freshwater, marine, and terrestrial hosts by adopting strategies convergent to those of parasitic protists. Myxozoans are estimated to represent some 20% of described cnidarian species-greatly outnumbering the combined species richness of scyphozoans, cubozoans, and staurozoans. We summarize limited understanding of myxozoan diversification and geographical distributions, and highlight gaps in knowledge and approaches for measuring myxozoan diversity. We close by reviewing methods and problems in estimating parasite extinction and concerns about extinction risks in view of the fundamental roles parasites play in ecosystem dynamics and in driving host evolutionary trajectories.
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Affiliation(s)
- Beth Okamura
- Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Ashlie Hartigan
- Department of Life Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Juliana Naldoni
- Departamento de Ciências Biológicas, Universidade Federal de São Paulo (UNIFESP), Diadema, SP 09972-270, Brazil
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5
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Bailey C, Rubin A, Strepparava N, Segner H, Rubin JF, Wahli T. Do fish get wasted? Assessing the influence of effluents on parasitic infection of wild fish. PeerJ 2018; 6:e5956. [PMID: 30479904 PMCID: PMC6238765 DOI: 10.7717/peerj.5956] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 10/17/2018] [Indexed: 12/12/2022] Open
Abstract
Many ecosystems are influenced simultaneously by multiple stressors. One important environmental stressor is aquatic pollution via wastewater treatment plant (WWTP) effluents. WWTP effluents may contribute to eutrophication or contain anthropogenic contaminants that directly and/or indirectly influence aquatic wildlife. Both eutrophication and exposure to anthropogenic contaminants may affect the dynamics of fish-parasite systems. With this in mind, we studied the impact of WWTP effluents on infection of brown trout by the parasite Tetracapsuloides bryosalmonae, the causative agent of proliferative kidney disease (PKD). PKD is associated with the long-term decline of wild brown trout (Salmo trutta) populations in Switzerland. We investigated PKD infection of brown trout at two adjacent sites (≈400 m apart) of a Swiss river. The sites are similar in terms of ecology except that one site receives WWTP effluents. We evaluated the hypothesis that fish inhabiting the effluent site will show greater susceptibility to PKD in terms of prevalence and disease outcome. We assessed susceptibility by (i) infection prevalence, (ii) parasite intensity, (iii) host health in terms of pathology, and (iv) estimated apparent survival rate. At different time points during the study, significant differences between sites concerning all measured parameters were found, thus providing evidence of the influence of effluents on parasitic infection of fish in our study system. However, from these findings we cannot determine if the effluent has a direct influence on the fish host via altering its ability to manage the parasite, or indirectly on the parasite or the invertebrate host via increasing bryozoa (the invertebrate host) reproduction. On a final note, the WWTP adhered to all national guidelines and the effluent only resulted in a minor water quality reduction assessed via standardized methods in this study. Thus, we provide evidence that even a subtle decrease in water quality, resulting in small-scale pollution can have consequences for wildlife.
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Affiliation(s)
- Christyn Bailey
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, Centre for Fish and Wildlife Health, University of Bern, Bern, Switzerland
| | - Aurélie Rubin
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, Centre for Fish and Wildlife Health, University of Bern, Bern, Switzerland.,University of Applied Sciences, Hepia, Geneva, Switzerland
| | - Nicole Strepparava
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, Centre for Fish and Wildlife Health, University of Bern, Bern, Switzerland
| | - Helmut Segner
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, Centre for Fish and Wildlife Health, University of Bern, Bern, Switzerland
| | - Jean-François Rubin
- University of Applied Sciences, Hepia, Geneva, Switzerland.,Maison de la Rivière, Tolochenaz, Switzerland
| | - Thomas Wahli
- Department of Infectious Diseases and Pathobiology, Vetsuisse Faculty, Centre for Fish and Wildlife Health, University of Bern, Bern, Switzerland
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6
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Gopko M, Chowdhury MMR, Taskinen J. Interactions between two parasites of brown trout ( Salmo trutta): Consequences of preinfection. Ecol Evol 2018; 8:9986-9997. [PMID: 30397441 PMCID: PMC6206180 DOI: 10.1002/ece3.4406] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 06/22/2018] [Accepted: 06/29/2018] [Indexed: 11/18/2022] Open
Abstract
Preinfection by one parasitic species may facilitate or by contrast hamper the subsequent penetration and/or establishment of other parasites in a host. The biology of interacting species, timing of preinfection, and dosage of subsequent parasite exposure are likely important variables in this multiparasite dynamic infection process. The increased vulnerability to subsequent infection can be an important and often overlooked factor influencing parasite virulence. We investigated how the preinfection by freshwater pearl mussel Margaritifera margaritifera glochidia could influence the success of subsequent infection by the common trematode Diplostomum pseudospathaceum in brown trout Salmo trutta and vice versa whether preinfection by the trematode made fish more susceptible to glochidia infection. The first experiment was repeated twice with different (low and high) exposure doses to initiate the subsequent trematode infection, while in the second experiment we varied the timing of the preinfection with trematodes. The preinfection with glochidia made fish more vulnerable to subsequent infection with trematodes. Since the trematodes penetrate through the gills, we suggest that increased host vulnerability was most likely the result of increased respiration caused by the freshwater pearl mussel glochidia encysted on gills. In turn, brown trout preinfected with trematodes were more vulnerable to the subsequent glochidial infection, but only if they were preinfected shortly before the subsequent infection (20 hr). Fish preinfected with trematodes earlier (2 weeks before the subsequent infection) did not differ in their vulnerability to glochidia. These effects were observed at moderate intensities of infections similar to those that occur in nature. Our study demonstrates how the timing and sequence of exposure to parasitic species can influence infection success in a host-multiparasite system. It indicates that the negative influence of glochidia on host fitness is likely to be underestimated and that this should be taken into consideration when organizing freshwater pearl mussel restoration procedures.
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Affiliation(s)
- Mikhail Gopko
- A.N. Severtsov Institute of Ecology and EvolutionRussian Academy of SciencesMoscowRussia
| | - M. Motiur R. Chowdhury
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyvaskylaFinland
| | - Jouni Taskinen
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyvaskylaFinland
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7
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Cohen C, Shemesh M, Garrido M, Messika I, Einav M, Khokhlova I, Tasker S, Hawlena H. Haemoplasmas in wild rodents: Routes of transmission and infection dynamics. Mol Ecol 2018; 27:3714-3726. [PMID: 30074652 DOI: 10.1111/mec.14826] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 07/04/2018] [Accepted: 07/19/2018] [Indexed: 01/06/2023]
Abstract
The way that some parasites and pathogens persist in the hostile environment of their host for long periods remains to be resolved. Here, longitudinal field surveys were combined with laboratory experiments to investigate the routes of transmission and infection dynamics of such a pathogen-a wild rodent haemotropic bacterium, specifically a Mycoplasma haemomuris-like bacterium. Fleaborne transmission, direct rodent-to-rodent transmission and vertical transmission from fleas or rodents to their offspring were experimentally quantified, and indications were found that the main route of bacterial transmission is direct, although its rate of successful transmission is low (~20%). The bacterium's temporal dynamics was then compared in the field to that observed under a controlled infection experiment in field-infected and laboratory-infected rodents, and indications were found, under all conditions, that the bacterium reached its peak infection level after 25-45 days and then decreased to low bacterial loads, which persist for the rodent's lifetime. These findings suggest that the bacterium relies on persistency with low bacterial loads for long-term coexistence with its rodent host, having both conceptual and applied implications.
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Affiliation(s)
- Carmit Cohen
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Merav Shemesh
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Mario Garrido
- Mitrani Department of Desert Ecology, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Irit Messika
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Monica Einav
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Irina Khokhlova
- Wyler Department of Dryland Agriculture, French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Séverine Tasker
- School of Veterinary Sciences, University of Bristol, Langford, UK
| | - Hadas Hawlena
- Mitrani Department of Desert Ecology, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
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8
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Antonovics J, Wilson AJ, Forbes MR, Hauffe HC, Kallio ER, Leggett HC, Longdon B, Okamura B, Sait SM, Webster JP. The evolution of transmission mode. Philos Trans R Soc Lond B Biol Sci 2017; 372:rstb.2016.0083. [PMID: 28289251 PMCID: PMC5352810 DOI: 10.1098/rstb.2016.0083] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/05/2016] [Indexed: 12/31/2022] Open
Abstract
This article reviews research on the evolutionary mechanisms leading to different transmission modes. Such modes are often under genetic control of the host or the pathogen, and often in conflict with each other via trade-offs. Transmission modes may vary among pathogen strains and among host populations. Evolutionary changes in transmission mode have been inferred through experimental and phylogenetic studies, including changes in transmission associated with host shifts and with evolution of the unusually complex life cycles of many parasites. Understanding the forces that determine the evolution of particular transmission modes presents a fascinating medley of problems for which there is a lack of good data and often a lack of conceptual understanding or appropriate methodologies. Our best information comes from studies that have been focused on the vertical versus horizontal transmission dichotomy. With other kinds of transitions, theoretical approaches combining epidemiology and population genetics are providing guidelines for determining when and how rapidly new transmission modes may evolve, but these are still in need of empirical investigation and application to particular cases. Obtaining such knowledge is a matter of urgency in relation to extant disease threats.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'.
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Affiliation(s)
- Janis Antonovics
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Anthony J Wilson
- Integrative Entomology group, Vector-borne Viral Diseases programme, The Pirbright Institute, Pirbright GU24 0NF, UK
| | - Mark R Forbes
- Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B7
| | - Heidi C Hauffe
- Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38010 S. Michele all'Adige, Trentino, Italy
| | - Eva R Kallio
- Department of Biological and Environmental Science, University of Jyvaskyla, PO Box 35, 40014 Jyvaskyla, Finland.,Department of Ecology, University of Oulu, PO Box 3000, 90014 Oulu, Finland
| | - Helen C Leggett
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Ben Longdon
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK
| | - Beth Okamura
- Department of Life Sciences, Natural History Museum, Cromwell Road, London SW5 7BD, UK
| | - Steven M Sait
- School of Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Joanne P Webster
- Department of Pathology and Pathogen Biology, Centre for Emerging, Endemic and Exotic Diseases, Royal Veterinary College, University of London, London AL9 7TA, UK
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9
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Fontes I, Hartikainen H, Williams C, Okamura B. Persistence, impacts and environmental drivers of covert infections in invertebrate hosts. Parasit Vectors 2017; 10:542. [PMID: 29096700 PMCID: PMC5668978 DOI: 10.1186/s13071-017-2495-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 10/23/2017] [Indexed: 11/10/2022] Open
Abstract
Background Persistent covert infections of the myxozoan, Tetracapsuloides bryosalmonae, in primary invertebrate hosts (the freshwater bryozoan, Fredericella sultana) have been proposed to represent a reservoir for proliferative kidney disease in secondary fish hosts. However, we have limited understanding of how covert infections persist and vary in bryozoan populations over time and space and how they may impact these populations. In addition, previous studies have likely underestimated covert infection prevalence. To improve our understanding of the dynamics, impacts and implications of covert infections we employed a highly sensitive polymerase chain reaction (PCR) assay and undertook the first investigation of covert infections in the field over an annual period by sampling bryozoans every 45 days from three populations within each of three rivers. Results Covert infections persisted throughout the year and prevalence varied within and between rivers, but were often > 50%. Variation in temperature and water chemistry were linked with changes in prevalence in a manner consistent with the maintenance of covert infections during periods of low productivity and thus poor growth conditions for both bryozoans and T. bryosalmonae. The presence and increased severity of covert infections reduced host growth but only when bryozoans were also investing in the production of overwintering propagules (statoblasts). However, because statoblast production is transitory, this effect is unlikely to greatly impact the capacity of bryozoan populations to act as persistent sources of infections and hence potential disease outbreaks in farmed and wild fish populations. Conclusions We demonstrate that covert infections are widespread and persist over space and time in bryozoan populations. To our knowledge, this is the first long-term study of covert infections in a field setting. Review of the results of this and previous studies enables us to identify key questions related to the ecology and evolution of covert infection strategies and associated host-parasite interactions. Electronic supplementary material The online version of this article (10.1186/s13071-017-2495-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Inês Fontes
- Department of Life Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK.,Scottish Fish Immunology Research Centre, Aberdeen University, Aberdeen, AB24 2TZ, UK
| | - Hanna Hartikainen
- EAWAG, Department of Aquatic Ecology, Überlandstrasse 133, CH-8600, Dübendorf, Switzerland.,ETH Zürich, Institute of Integrative Biology (IBZ), Zürich, Switzerland
| | - Chris Williams
- Environment Agency, National Fisheries Laboratory, Brampton, Cambridgeshire, PE28 4NE, UK
| | - Beth Okamura
- Department of Life Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK.
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10
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Williams T, Virto C, Murillo R, Caballero P. Covert Infection of Insects by Baculoviruses. Front Microbiol 2017; 8:1337. [PMID: 28769903 PMCID: PMC5511839 DOI: 10.3389/fmicb.2017.01337] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 07/03/2017] [Indexed: 12/19/2022] Open
Abstract
Baculoviruses (Baculoviridae) are occluded DNA viruses that are lethal pathogens of the larval stages of some lepidopterans, mosquitoes, and sawflies (phytophagous Hymenoptera). These viruses have been developed as biological insecticides for control of insect pests and as expression vectors in biotechnological applications. Natural and laboratory populations frequently harbor covert infections by baculoviruses, often at a prevalence exceeding 50%. Covert infection can comprise either non-productive latency or sublethal infection involving low level production of virus progeny. Latency in cell culture systems involves the expression of a small subset of viral genes. In contrast, covert infection in lepidopterans is associated with differential infection of cell types, modulation of virus gene expression and avoidance of immune system clearance. The molecular basis for covert infection may reside in the regulation of host-virus interactions through the action of microRNAs (miRNA). Initial findings suggest that insect nudiviruses and vertebrate herpesviruses may provide useful analogous models for exploring the mechanisms of covert infection by baculoviruses. These pathogens adopt mixed-mode transmission strategies that depend on the relative fitness gains that accrue through vertical and horizontal transmission. This facilitates virus persistence when opportunities for horizontal transmission are limited and ensures virus dispersal in migratory host species. However, when host survival is threatened by environmental or physiological stressors, latent or persistent infections can be activated to produce lethal disease, followed by horizontal transmission. Covert infection has also been implicated in population level effects on host-pathogen dynamics due to the reduced reproductive capacity of infected females. We conclude that covert infections provide many opportunities to examine the complexity of insect-virus pathosystems at the organismal level and to explore the evolutionary and ecological relationships of these pathogens with major crop and forest pests.
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Affiliation(s)
| | - Cristina Virto
- Bioinsecticidas Microbianos, Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas, Universidad Pública de NavarraMutilva, Spain
- Laboratorio de Entomología Agrícola y Patología de Insectos, Departamento de Producción Agraria, Universidad Pública de NavarraPamplona, Spain
| | - Rosa Murillo
- Bioinsecticidas Microbianos, Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas, Universidad Pública de NavarraMutilva, Spain
- Laboratorio de Entomología Agrícola y Patología de Insectos, Departamento de Producción Agraria, Universidad Pública de NavarraPamplona, Spain
| | - Primitivo Caballero
- Bioinsecticidas Microbianos, Instituto de Agrobiotecnología, Consejo Superior de Investigaciones Científicas, Universidad Pública de NavarraMutilva, Spain
- Laboratorio de Entomología Agrícola y Patología de Insectos, Departamento de Producción Agraria, Universidad Pública de NavarraPamplona, Spain
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11
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Conditional persistence and tolerance characterize endoparasite-colonial host interactions. Parasitology 2017; 144:1052-1063. [PMID: 28290261 DOI: 10.1017/s0031182017000269] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Colonial hosts offer unique opportunities for exploitation by endoparasites resulting from extensive clonal propagation, but these interactions are poorly understood. The freshwater bryozoan, Fredericella sultana, and the myxozoan, Tetracapsuloides bryosalmonae, present an appropriate model system for examining such interactions. F. sultana propagates mainly asexually, through colony fragmentation and dormant propagules (statoblasts). Our study examines how T. bryosalmonae exploits the multiple transmission routes offered by the propagation of F. sultana, evaluates the effects of such transmission on its bryozoan host, and tests the hypothesis that poor host condition provokes T. bryosalmonae to bail out of a resource that may soon be unsustainable, demonstrating terminal investment. We show that infections are present in substantial proportions of colony fragments and statoblasts over space and time and that moderate infection levels promote statoblast hatching and hence effective fecundity. We also found evidence for terminal investment, with host starvation inducing the development of transmission stages. Our results contribute to a growing picture that interactions of T. bryosalmonae and F. sultana are generally characterized by parasite persistence, facilitated by multiple transmission pathways and host condition-dependent developmental cycling, and host tolerance, promoted by effective fecundity effects and an inherent capacity for renewed growth and clonal replication.
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12
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Costello MJ. Parasite Rates of Discovery, Global Species Richness and Host Specificity. Integr Comp Biol 2016; 56:588-99. [PMID: 27400977 DOI: 10.1093/icb/icw084] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
If every metazoan species has at least one host-specific parasite, as several local scale studies have suggested, then half of all species could be parasites. However, host specificity varies significantly depending on host phylogeny, body size, habitat, and geographic distribution. The best studied hosts tend to be vertebrates, larger animals, and/or widespread, and thus have a higher number of parasites and host-specific parasites. Thus, host specificity for these well-known taxa cannot be simply extrapolated to other taxa, notably invertebrates, small sized, and more endemic species, which comprise the major portion of yet to be discovered species. At present, parasites of animals comprise about 5% of named species. This article analyzed the rate of description of several largely parasitic taxa within crustaceans (copepods, amphipods, isopods, pentastomids, cirripeds), marine helminths (nematodes, acanthocephalans, flukes), gastropod molluscs, insects (ticks, fleas, biting flies, strepispterans), and microsporidia. The period of highest discovery has been most recent for the marine helminths and microsporids. The number of people describing parasites has been increasing since the 1960s, as it has for all other taxa. However, the number of species being described per decade relative to the number of authors has been decreasing except for the helminths. The results indicate that more than half of all parasites have been described, and two-thirds of host taxa, although the proportion varies between taxa. It is highly unlikely that the number of named species of parasites will ever approach that of their hosts. This contrast between the proportion that parasites comprise of local and global faunas suggests that parasites are less host specific and more widespread than local scale studies suggest.
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Affiliation(s)
- Mark John Costello
- Institute of Marine Science, University of Auckland, Auckland, 1142, New Zealand
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Marcogliese DJ. The Distribution and Abundance of Parasites in Aquatic Ecosystems in a Changing Climate: More than Just Temperature. Integr Comp Biol 2016; 56:611-9. [PMID: 27252206 DOI: 10.1093/icb/icw036] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
SynopsisEvaluation of the potential response of parasites of aquatic organisms to climate change illustrates the complexity of host-parasite relationships and the difficulty of making accurate predictions for these biological systems. In recent years, trematodes have proven to be a useful model to evaluate potential effects of climate change on host-parasite systems. In the first part of this article, I review and summarize results from the recent use of trematodes and specifically their early life cycle stages in testing effects of temperature and other climate-driven variables on life history traits and host-parasite interactions. However, metazoan parasites in aquatic systems respond directly to changes in temperature and also to changes in other climate-driven abiotic parameters that are mediated directly on the parasite or indirectly through changes in the distribution and abundance of their hosts. In addition, though most research to date has focused on the effects of temperature, it is imperative to explore effects of precipitation, eutrophication, acidification, water levels and flow rates, habitat loss and fragmentation, extreme weather, and other forms of anthropogenic interference on the distribution of both hosts and parasites, as these biotic and abiotic factors and stressors do not operate independently of climate. In the second part of this article, the effects of some of these factors derived from our own field studies, as well as other investigations both in the laboratory and the field, on the distribution, abundance, and community structure of parasites in aquatic ecosystems will be reviewed and discussed.
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Affiliation(s)
- David J Marcogliese
- Aquatic Contaminants Research Division, Water Science and Technology Directorate, Science and Technology Branch, Environment and Climate Change Canada, St. Lawrence Centre, 105 McGill, 7th floor, Montreal, Quebec, Canada H2Y 2E7
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