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Gratwicke B, Savage A. Mini saunas save endangered frogs from fungal disease. Nature 2024:10.1038/d41586-024-01650-z. [PMID: 38926557 DOI: 10.1038/d41586-024-01650-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2024]
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2
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Martin CA, Sheppard EC, Ali HAA, Illera JC, Suh A, Spurgin LG, Richardson DS. Genomic landscapes of divergence among island bird populations: Evidence of parallel adaptation but at different loci? Mol Ecol 2024; 33:e17365. [PMID: 38733214 DOI: 10.1111/mec.17365] [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: 02/26/2023] [Accepted: 03/01/2024] [Indexed: 05/13/2024]
Abstract
When populations colonise new environments, they may be exposed to novel selection pressures but also suffer from extensive genetic drift due to founder effects, small population sizes and limited interpopulation gene flow. Genomic approaches enable us to study how these factors drive divergence, and disentangle neutral effects from differentiation at specific loci due to selection. Here, we investigate patterns of genetic diversity and divergence using whole-genome resequencing (>22× coverage) in Berthelot's pipit (Anthus berthelotii), a passerine endemic to the islands of three north Atlantic archipelagos. Strong environmental gradients, including in pathogen pressure, across populations in the species range, make it an excellent system in which to explore traits important in adaptation and/or incipient speciation. First, we quantify how genomic divergence accumulates across the speciation continuum, that is, among Berthelot's pipit populations, between sub species across archipelagos, and between Berthelot's pipit and its mainland ancestor, the tawny pipit (Anthus campestris). Across these colonisation timeframes (2.1 million-ca. 8000 years ago), we identify highly differentiated loci within genomic islands of divergence and conclude that the observed distributions align with expectations for non-neutral divergence. Characteristic signatures of selection are identified in loci associated with craniofacial/bone and eye development, metabolism and immune response between population comparisons. Interestingly, we find limited evidence for repeated divergence of the same loci across the colonisation range but do identify different loci putatively associated with the same biological traits in different populations, likely due to parallel adaptation. Incipient speciation across these island populations, in which founder effects and selective pressures are strong, may therefore be repeatedly associated with morphology, metabolism and immune defence.
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Affiliation(s)
- Claudia A Martin
- School of Biological Sciences, University of East Anglia, Norfolk, UK
- Terrestrial Ecology Unit, Biology Department, Ghent University, Ghent, Belgium
- School of Biological Sciences, The University of Edinburgh, Edinburgh, UK
| | | | - Hisham A A Ali
- Department of Biology, Edward Grey Institute of Field Ornithology, University of Oxford, Oxford, UK
| | - Juan Carlos Illera
- Biodiversity Research Institute (CSIC-Oviedo University-Principality of Asturias), University of Oviedo, Mieres, Asturias, Spain
| | - Alexander Suh
- School of Biological Sciences, University of East Anglia, Norfolk, UK
- Department of Organismal Biology - Systematic Biology, Evolutionary Biology Centre (EBC), Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Lewis G Spurgin
- School of Biological Sciences, University of East Anglia, Norfolk, UK
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3
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Carvalho T, Belasen AM, Toledo LF, James TY. Coevolution of a generalist pathogen with many hosts: the case of the amphibian chytrid Batrachochytrium dendrobatidis. Curr Opin Microbiol 2024; 78:102435. [PMID: 38387210 DOI: 10.1016/j.mib.2024.102435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 12/22/2023] [Accepted: 01/21/2024] [Indexed: 02/24/2024]
Abstract
Generalist pathogens maintain infectivity in numerous hosts; how this broad ecological niche impacts host-pathogen coevolution remains to be widely explored. Batrachochytrium dendrobatidis (Bd) is a highly generalist pathogenic fungus that has caused devastating declines in hundreds of amphibian species worldwide. This review examines amphibian chytridiomycosis host-pathogen interactions and available evidence for coevolution between Bd and its numerous hosts. We summarize recent evidence showing that Bd genotypes vary in geographic distribution and virulence, and that amphibian species also vary in Bd susceptibility according to their geographic distribution. How much variation can be explained by phenotypic plasticity or genetic differences remains uncertain. Recent research suggests that Bd genotypes display preferences for specific hosts and that some hosts are undergoing evolution as populations rebound from Bd outbreaks. Taken together, these findings suggest the potential for coevolution to occur and illuminate a path for addressing open questions through integrating historical and contemporary genetic data.
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Affiliation(s)
- Tamilie Carvalho
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, United States
| | - Anat M Belasen
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, United States
| | - L Felipe Toledo
- Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Unicamp, Campinas, São Paulo, Brazil
| | - Timothy Y James
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, United States.
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4
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Raven N, Klaassen M, Madsen T, Jones M, Hamilton DG, Ruiz-Aravena M, Thomas F, Hamede RK, Ujvari B. Complex associations between cancer progression and immune gene expression reveals early influence of transmissible cancer on Tasmanian devils. Front Immunol 2024; 15:1286352. [PMID: 38515744 PMCID: PMC10954821 DOI: 10.3389/fimmu.2024.1286352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 01/29/2024] [Indexed: 03/23/2024] Open
Abstract
The world's largest extant carnivorous marsupial, the Tasmanian devil, is challenged by Devil Facial Tumor Disease (DFTD), a fatal, clonally transmitted cancer. In two decades, DFTD has spread across 95% of the species distributional range. A previous study has shown that factors such as season, geographic location, and infection with DFTD can impact the expression of immune genes in Tasmanian devils. To date, no study has investigated within-individual immune gene expression changes prior to and throughout the course of DFTD infection. To explore possible changes in immune response, we investigated four locations across Tasmania that differed in DFTD exposure history, ranging between 2 and >30 years. Our study demonstrated considerable complexity in the immune responses to DFTD. The same factors (sex, age, season, location and DFTD infection) affected immune gene expression both across and within devils, although seasonal and location specific variations were diminished in DFTD affected devils. We also found that expression of both adaptive and innate immune genes starts to alter early in DFTD infection and continues to change as DFTD progresses. A novel finding was that the lower expression of immune genes MHC-II, NKG2D and CD8 may predict susceptibility to earlier DFTD infection. A case study of a single devil with regressed tumor showed opposite/contrasting immune gene expression patterns compared to the general trends observed across devils with DFTD infection. Our study highlights the complexity of DFTD's interactions with the host immune system and the need for long-term studies to fully understand how DFTD alters the evolutionary trajectory of devil immunity.
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Affiliation(s)
- Nynke Raven
- Deakin University, School of Life and Environmental Sciences, Centre for Integrative Ecology, Geelong, VIC, Australia
| | - Marcel Klaassen
- Deakin University, School of Life and Environmental Sciences, Centre for Integrative Ecology, Geelong, VIC, Australia
| | - Thomas Madsen
- Deakin University, School of Life and Environmental Sciences, Centre for Integrative Ecology, Geelong, VIC, Australia
| | - Menna Jones
- School of Natural Sciences, University of Tasmania, Hobart, TAS, Australia
| | - David G. Hamilton
- School of Natural Sciences, University of Tasmania, Hobart, TAS, Australia
| | - Manuel Ruiz-Aravena
- Mississippi State University, Forest & Wildlife Research Center (FWRC)-Wildlife, Fisheries & Aquaculture, Starkville, MS, United States
| | - Frederic Thomas
- CREEC/CANECEV, CREES-MIVEGEC, Univ. Montpellier, CNRS, IRD, Montpellier, France
| | - Rodrigo K. Hamede
- School of Natural Sciences, University of Tasmania, Hobart, TAS, Australia
| | - Beata Ujvari
- Deakin University, School of Life and Environmental Sciences, Centre for Integrative Ecology, Geelong, VIC, Australia
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5
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Mulder KP, Savage AE, Gratwicke B, Longcore JE, Bronikowski E, Evans M, Longo AV, Kurata NP, Walsh T, Pasmans F, McInerney N, Murray S, Martel A, Fleischer RC. Sequence capture identifies fastidious chytrid fungi directly from host tissue. Fungal Genet Biol 2024; 170:103858. [PMID: 38101696 DOI: 10.1016/j.fgb.2023.103858] [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: 04/20/2023] [Revised: 12/04/2023] [Accepted: 12/12/2023] [Indexed: 12/17/2023]
Abstract
The chytrid fungus Batrachochytrium dendrobatidis (Bd) was discovered in 1998 as the cause of chytridiomycosis, an emerging infectious disease causing mass declines in amphibian populations worldwide. The rapid population declines of the 1970s-1990s were likely caused by the spread of a highly virulent lineage belonging to the Bd-GPL clade that was introduced to naïve susceptible populations. Multiple genetically distinct and regional lineages of Bd have since been isolated and sequenced, greatly expanding the known biological diversity within this fungal pathogen. To date, most Bd research has been restricted to the limited number of samples that could be isolated using culturing techniques, potentially causing a selection bias for strains that can grow on media and missing other unculturable or fastidious strains that are also present on amphibians. We thus attempted to characterize potentially non-culturable genetic lineages of Bd from distinct amphibian taxa using sequence capture technology on DNA extracted from host tissue and swabs. We focused our efforts on host taxa from two different regions that likely harbored distinct Bd clades: (1) wild-caught leopard frogs (Rana) from North America, and (2) a Japanese Giant Salamander (Andrias japonicus) at the Smithsonian Institution's National Zoological Park that exhibited signs of disease and tested positive for Bd using qPCR, but multiple attempts failed to isolate and culture the strain for physiological and genetic characterization. We successfully enriched for and sequenced thousands of fungal genes from both host clades, and Bd load was positively associated with number of recovered Bd sequences. Phylogenetic reconstruction placed all the Rana-derived strains in the Bd-GPL clade. In contrast, the A. japonicus strain fell within the Bd-Asia3 clade, expanding the range of this clade and generating additional genomic data to confirm its placement. The retrieved ITS locus matched public barcoding data from wild A. japonicus and Bd infections found on other amphibians in India and China, suggesting that this uncultured clade is widespread across Asia. Our study underscores the importance of recognizing and characterizing the hidden diversity of fastidious strains in order to reconstruct the spatiotemporal and evolutionary history of Bd. The success of the sequence capture approach highlights the utility of directly sequencing pathogen DNA from host tissue to characterize cryptic diversity that is missed by culture-reliant approaches.
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Affiliation(s)
- Kevin P Mulder
- Wildlife Health Ghent, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium; Center for Conservation Genomics, Smithsonian National Zoo and Conservation Biology Institute, Washington, DC, USA.
| | - Anna E Savage
- Department of Biology, University of Central Florida, Orlando, FL, USA
| | - Brian Gratwicke
- Smithsonian's National Zoo and Conservation Biology Institute, Washington, DC, USA
| | - Joyce E Longcore
- School of Biology and Ecology, University of Maine, Orono, ME, USA
| | - Ed Bronikowski
- Smithsonian's National Zoo and Conservation Biology Institute, Washington, DC, USA
| | - Matthew Evans
- Smithsonian's National Zoo and Conservation Biology Institute, Washington, DC, USA
| | - Ana V Longo
- Department of Biology, University of Florida, Gainesville, FL, USA
| | - Naoko P Kurata
- Center for Conservation Genomics, Smithsonian National Zoo and Conservation Biology Institute, Washington, DC, USA; Department of Natural Resources and the Environment, Cornell University, Ithaca, NY, USA; Department of Ichthyology, American Museum of Natural History, New York, NY, USA
| | - Tim Walsh
- Smithsonian's National Zoo and Conservation Biology Institute, Washington, DC, USA
| | - Frank Pasmans
- Wildlife Health Ghent, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Nancy McInerney
- Center for Conservation Genomics, Smithsonian National Zoo and Conservation Biology Institute, Washington, DC, USA
| | - Suzan Murray
- Smithsonian's National Zoo and Conservation Biology Institute, Washington, DC, USA
| | - An Martel
- Wildlife Health Ghent, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Robert C Fleischer
- Center for Conservation Genomics, Smithsonian National Zoo and Conservation Biology Institute, Washington, DC, USA
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Chondrelli N, Kuehn E, Meurling S, Cortázar-Chinarro M, Laurila A, Höglund J. Batrachochytrium dendrobatidis strain affects transcriptomic response in liver but not skin in latitudinal populations of the common toad (Bufo bufo). Sci Rep 2024; 14:2495. [PMID: 38291226 PMCID: PMC10828426 DOI: 10.1038/s41598-024-52975-8] [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: 09/07/2023] [Accepted: 01/25/2024] [Indexed: 02/01/2024] Open
Abstract
Batrachochytrium dendrobatidis (Bd) is a fungal pathogen that has decimated amphibian populations worldwide for several decades. We examined the changes in gene expression in response to Bd infection in two populations of the common toad, Bufo bufo, in a laboratory experiment. We collected B. bufo eggs in southern and northern Sweden, and infected the laboratory-raised metamorphs with two strains of the global panzoonotic lineage Bd-GPL. Differential expression analysis showed significant differences between infected and control individuals in both liver and skin. The skin samples showed no discernible differences in gene expression between the two strains used, while liver samples were differentiated by strain, with one of the strains eliciting no immune response from infected toads. Immune system genes were overexpressed in skin samples from surviving infected individuals, while in liver samples the pattern was more diffuse. Splitting samples by population revealed a stronger immune response in northern individuals. Differences in transcriptional regulation between populations are particularly relevant to study in Swedish amphibians, which may have experienced varying exposure to Bd. Earlier exposure to this pathogen and subsequent adaptation or selection pressure may contribute to the survival of some populations over others, while standing genetic diversity in different populations may also affect the infection outcome.
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Affiliation(s)
- Niki Chondrelli
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden.
| | - Emily Kuehn
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - Sara Meurling
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - Maria Cortázar-Chinarro
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
- MEMEG/Department of Biology, Faculty of Science, Lund University, Lund, Sweden
| | - Anssi Laurila
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - Jacob Höglund
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
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7
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Mathur S, Haynes E, Allender MC, Gibbs HL. Genetic mechanisms and biological processes underlying host response to ophidiomycosis (snake fungal disease) inferred from tissue-specific transcriptome analyses. Mol Ecol 2024; 33:e17210. [PMID: 38010927 DOI: 10.1111/mec.17210] [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: 04/06/2023] [Revised: 07/28/2023] [Accepted: 11/06/2023] [Indexed: 11/29/2023]
Abstract
Emerging infectious diseases in wildlife species caused by pathogenic fungi are of growing concern, yet crucial knowledge gaps remain for diseases with potentially large impacts. For example, there is detailed knowledge about host pathology and mechanisms underlying response for chytridiomycosis in amphibians and white-nose syndrome in bats, but such information is lacking for other more recently described fungal infections. One such disease is ophidiomycosis, caused by the fungus Ophidiomyces ophidiicola, which has been identified in many species of snakes, yet the biological mechanisms and molecular changes occurring during infection are unknown. To gain this information, we performed a controlled experimental infection in captive Prairie rattlesnakes (Crotalus viridis) with O. ophidiicola at two different temperatures: 20 and 26°C. We then compared liver, kidney, and skin transcriptomes to assess tissue-specific genetic responses to O. ophidiicola infection. Given previous histopathological studies and the fact that snakes are ectotherms, we expected highest fungal activity on skin and a significant impact of temperature on host response. Although we found fungal activity to be localized on skin, most of the differential gene expression occurred in internal tissues. Infected snakes at the lower temperature had the highest host mortality whereas two-thirds of the infected snakes at the higher temperature survived. Our results suggest that ophidiomycosis is likely a systemic disease with long-term effects on host response. Our analysis also identified candidate protein coding genes that are potentially involved in host response, providing genetic tools for studies of host response to ophidiomycosis in natural populations.
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Affiliation(s)
- Samarth Mathur
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, Ohio, USA
- Ohio Biodiversity Conservation Partnership, The Ohio State University, Columbus, Ohio, USA
| | - Ellen Haynes
- Wildlife Epidemiology Laboratory, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Southeastern Cooperative Wildlife Disease Study, University of Georgia, Athens, Georgia, USA
| | - Matthew C Allender
- Wildlife Epidemiology Laboratory, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Brookfield Zoo, Chicago Zoological Society, Brookfield, Illinois, USA
| | - H Lisle Gibbs
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, Ohio, USA
- Ohio Biodiversity Conservation Partnership, The Ohio State University, Columbus, Ohio, USA
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8
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Ruiz VL, Robert J. The amphibian immune system. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220123. [PMID: 37305914 PMCID: PMC10258673 DOI: 10.1098/rstb.2022.0123] [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: 02/05/2023] [Accepted: 04/16/2023] [Indexed: 06/13/2023] Open
Abstract
Amphibians are at the forefront of bridging the evolutionary gap between mammals and more ancient, jawed vertebrates. Currently, several diseases have targeted amphibians and understanding their immune system has importance beyond their use as a research model. The immune system of the African clawed frog, Xenopus laevis, and that of mammals is well conserved. We know that several features of the adaptive and innate immune system are very similar for both, including the existence of B cells, T cells and innate-like T cells. In particular, the study of the immune system at early stages of development is benefitted by studying X. laevis tadpoles. The tadpoles mainly rely on innate immune mechanisms including pre-set or innate-like T cells until after metamorphosis. In this review we lay out what is known about the innate and adaptive immune system of X. laevis including the lymphoid organs as well as how other amphibian immune systems are similar or different. Furthermore, we will describe how the amphibian immune system responds to some viral, bacterial and fungal insults. This article is part of the theme issue 'Amphibian immunity: stress, disease and ecoimmunology'.
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Affiliation(s)
- Vania Lopez Ruiz
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Jacques Robert
- Department of Microbiology and Immunology, University of Rochester Medical Center, Rochester, NY 14642, USA
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Paxton KL, Cassin-Sackett L, Atkinson CT, Videvall E, Campana MG, Fleischer RC. Gene expression reveals immune response strategies of naïve Hawaiian honeycreepers experimentally infected with introduced avian malaria. J Hered 2023; 114:326-340. [PMID: 36869776 DOI: 10.1093/jhered/esad017] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 03/01/2023] [Indexed: 03/05/2023] Open
Abstract
The unprecedented rise in the number of new and emerging infectious diseases in the last quarter century poses direct threats to human and wildlife health. The introduction to the Hawaiian archipelago of Plasmodium relictum and the mosquito vector that transmits the parasite has led to dramatic losses in endemic Hawaiian forest bird species. Understanding how mechanisms of disease immunity to avian malaria may evolve is critical as climate change facilitates increased disease transmission to high elevation habitats where malaria transmission has historically been low and the majority of the remaining extant Hawaiian forest bird species now reside. Here, we compare the transcriptomic profiles of highly susceptible Hawai'i 'amakihi (Chlorodrepanis virens) experimentally infected with P. relictum to those of uninfected control birds from a naïve high elevation population. We examined changes in gene expression profiles at different stages of infection to provide an in-depth characterization of the molecular pathways contributing to survival or mortality in these birds. We show that the timing and magnitude of the innate and adaptive immune response differed substantially between individuals that survived and those that succumbed to infection, and likely contributed to the observed variation in survival. These results lay the foundation for developing gene-based conservation strategies for Hawaiian honeycreepers by identifying candidate genes and cellular pathways involved in the pathogen response that correlate with a bird's ability to recover from malaria infection.
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Affiliation(s)
- Kristina L Paxton
- Center for Conservation Genomics, National Zoological Park and Conservation Biology Institute, Smithsonian Institution, Washington, DC 20008, USA
- Hawai'i Cooperative Studies Unit, University of Hawai'i Hilo, PO Box 44, Hawai'i National Park, HI 96718, USA
| | - Loren Cassin-Sackett
- Center for Conservation Genomics, National Zoological Park and Conservation Biology Institute, Smithsonian Institution, Washington, DC 20008, USA
- Department of Biology, University of Louisiana, Lafayette, LA 70503, USA
| | - Carter T Atkinson
- U.S. Geological Survey Pacific Island Ecosystems Research Center, PO Box 44, Hawai'i National Park, HI 96718, USA
| | - Elin Videvall
- Center for Conservation Genomics, National Zoological Park and Conservation Biology Institute, Smithsonian Institution, Washington, DC 20008, USA
- Department of Ecology, Evolution and Organismal Biology, Brown University, Providence, RI 02912, USA
| | - Michael G Campana
- Center for Conservation Genomics, National Zoological Park and Conservation Biology Institute, Smithsonian Institution, Washington, DC 20008, USA
| | - Robert C Fleischer
- Center for Conservation Genomics, National Zoological Park and Conservation Biology Institute, Smithsonian Institution, Washington, DC 20008, USA
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Vinkler M, Fiddaman SR, Těšický M, O'Connor EA, Savage AE, Lenz TL, Smith AL, Kaufman J, Bolnick DI, Davies CS, Dedić N, Flies AS, Samblás MMG, Henschen AE, Novák K, Palomar G, Raven N, Samaké K, Slade J, Veetil NK, Voukali E, Höglund J, Richardson DS, Westerdahl H. Understanding the evolution of immune genes in jawed vertebrates. J Evol Biol 2023; 36:847-873. [PMID: 37255207 PMCID: PMC10247546 DOI: 10.1111/jeb.14181] [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: 09/23/2022] [Revised: 04/23/2023] [Accepted: 04/26/2023] [Indexed: 06/01/2023]
Abstract
Driven by co-evolution with pathogens, host immunity continuously adapts to optimize defence against pathogens within a given environment. Recent advances in genetics, genomics and transcriptomics have enabled a more detailed investigation into how immunogenetic variation shapes the diversity of immune responses seen across domestic and wild animal species. However, a deeper understanding of the diverse molecular mechanisms that shape immunity within and among species is still needed to gain insight into-and generate evolutionary hypotheses on-the ultimate drivers of immunological differences. Here, we discuss current advances in our understanding of molecular evolution underpinning jawed vertebrate immunity. First, we introduce the immunome concept, a framework for characterizing genes involved in immune defence from a comparative perspective, then we outline how immune genes of interest can be identified. Second, we focus on how different selection modes are observed acting across groups of immune genes and propose hypotheses to explain these differences. We then provide an overview of the approaches used so far to study the evolutionary heterogeneity of immune genes on macro and microevolutionary scales. Finally, we discuss some of the current evidence as to how specific pathogens affect the evolution of different groups of immune genes. This review results from the collective discussion on the current key challenges in evolutionary immunology conducted at the ESEB 2021 Online Satellite Symposium: Molecular evolution of the vertebrate immune system, from the lab to natural populations.
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Affiliation(s)
- Michal Vinkler
- Department of ZoologyFaculty of ScienceCharles UniversityPragueCzech Republic
| | | | - Martin Těšický
- Department of ZoologyFaculty of ScienceCharles UniversityPragueCzech Republic
| | | | - Anna E. Savage
- Department of BiologyUniversity of Central FloridaFloridaOrlandoUSA
| | - Tobias L. Lenz
- Research Unit for Evolutionary ImmunogenomicsDepartment of BiologyUniversity of HamburgHamburgGermany
| | | | - Jim Kaufman
- Institute for Immunology and Infection ResearchUniversity of EdinburghEdinburghUK
- Department of Veterinary MedicineUniversity of CambridgeCambridgeUK
| | - Daniel I. Bolnick
- Department of Ecology and Evolutionary BiologyUniversity of ConnecticutStorrsConnecticutUSA
| | | | - Neira Dedić
- Department of Botany and ZoologyMasaryk UniversityBrnoCzech Republic
| | - Andrew S. Flies
- Menzies Institute for Medical ResearchUniversity of TasmaniaHobartTasmaniaAustralia
| | - M. Mercedes Gómez Samblás
- Department of ZoologyFaculty of ScienceCharles UniversityPragueCzech Republic
- Department of ParasitologyUniversity of GranadaGranadaSpain
| | | | - Karel Novák
- Department of Genetics and BreedingInstitute of Animal SciencePragueUhříněvesCzech Republic
| | - Gemma Palomar
- Faculty of BiologyInstitute of Environmental SciencesJagiellonian UniversityKrakówPoland
| | - Nynke Raven
- Department of ScienceEngineering and Build EnvironmentDeakin UniversityVictoriaWaurn PondsAustralia
| | - Kalifa Samaké
- Department of Genetics and MicrobiologyFaculty of ScienceCharles UniversityPragueCzech Republic
| | - Joel Slade
- Department of BiologyCalifornia State UniversityFresnoCaliforniaUSA
| | | | - Eleni Voukali
- Department of ZoologyFaculty of ScienceCharles UniversityPragueCzech Republic
| | - Jacob Höglund
- Department of Ecology and GeneticsUppsala UniversitetUppsalaSweden
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11
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Kaganer AW, Ossiboff RJ, Keith NI, Schuler KL, Comizzoli P, Hare MP, Fleischer RC, Gratwicke B, Bunting EM. Immune priming prior to pathogen exposure sheds light on the relationship between host, microbiome and pathogen in disease. ROYAL SOCIETY OPEN SCIENCE 2023; 10:220810. [PMID: 36756057 PMCID: PMC9890126 DOI: 10.1098/rsos.220810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 01/04/2023] [Indexed: 06/18/2023]
Abstract
Dynamic interactions between host, pathogen and host-associated microbiome dictate infection outcomes. Pathogens including Batrachochytrium dendrobatidis (Bd) threaten global biodiversity, but conservation efforts are hindered by limited understanding of amphibian host, Bd and microbiome interactions. We conducted a vaccination and infection experiment using Eastern hellbender salamanders (Cryptobranchus alleganiensis alleganiensis) challenged with Bd to observe infection, skin microbial communities and gene expression of host skin, pathogen and microbiome throughout the experiment. Most animals survived high Bd loads regardless of their vaccination status and vaccination did not affect pathogen load, but host gene expression differed based on vaccination. Oral vaccination (exposure to killed Bd) stimulated immune gene upregulation while topically and sham-vaccinated animals did not significantly upregulate immune genes. In early infection, topically vaccinated animals upregulated immune genes but orally and sham-vaccinated animals downregulated immune genes. Bd increased pathogenicity-associated gene expression in late infection when Bd loads were highest. The microbiome was altered by Bd, but there was no correlation between anti-Bd microbe abundance or richness and pathogen burden. Our observations suggest that hellbenders initially generate a vigorous immune response to Bd, which is ineffective at controlling disease and is subsequently modulated. Interactions with antifungal skin microbiota did not influence disease progression.
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Affiliation(s)
- Alyssa W. Kaganer
- Department of Natural Resources and the Environment, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, 14853, USA
- Smithsonian's National Zoo and Conservation Biology Institute, Washington, DC, 20008, USA
- Cornell Wildlife Health Laboratory, Animal Health Diagnostic Center, Cornell University, Ithaca, NY, 14853, USA
| | - Robert J. Ossiboff
- Cornell Wildlife Health Laboratory, Animal Health Diagnostic Center, Cornell University, Ithaca, NY, 14853, USA
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
- Department of Comparative, Diagnostic, and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, FL, 32611, USA
| | - Nicole I. Keith
- Cornell Wildlife Health Laboratory, Animal Health Diagnostic Center, Cornell University, Ithaca, NY, 14853, USA
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
- Biology Department, Hamilton College, Clinton, NY, 13323, USA
| | - Krysten L. Schuler
- Cornell Wildlife Health Laboratory, Animal Health Diagnostic Center, Cornell University, Ithaca, NY, 14853, USA
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
| | - Pierre Comizzoli
- Smithsonian's National Zoo and Conservation Biology Institute, Washington, DC, 20008, USA
| | - Matthew P. Hare
- Department of Natural Resources and the Environment, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, 14853, USA
| | - Robert C. Fleischer
- Smithsonian's National Zoo and Conservation Biology Institute, Washington, DC, 20008, USA
| | - Brian Gratwicke
- Smithsonian's National Zoo and Conservation Biology Institute, Front Royal, VA, 22630, USA
| | - Elizabeth M. Bunting
- Cornell Wildlife Health Laboratory, Animal Health Diagnostic Center, Cornell University, Ithaca, NY, 14853, USA
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
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12
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Woodring T, Deepe GS, Levitz SM, Wuethrich M, Klein BS. They shall not grow mold: Soldiers of innate and adaptive immunity to fungi. Semin Immunol 2023; 65:101673. [PMID: 36459927 PMCID: PMC10311222 DOI: 10.1016/j.smim.2022.101673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Indexed: 11/30/2022]
Abstract
Fungi are ubiquitous commensals, seasoned predators, and important agents of emerging infectious diseases [1 ]. The immune system assumes the essential responsibility for responding intelligently to the presence of known and novel fungi to maintain host health. In this Review, we describe the immune responses to pathogenic fungi and the varied array of fungal agents confronting the vertebrate host within the broader context of fungal and animal evolution. We provide an overview of the mechanistic details of innate and adaptive antifungal immune responses, as well as ways in which these basic mechanisms support the development of vaccines and immunotherapies.
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Affiliation(s)
- Therese Woodring
- Departments of Pediatrics, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison WI, USA
| | - George S Deepe
- Department of Medicine, Division of Infectious Diseases, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Stuart M Levitz
- Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Marcel Wuethrich
- Departments of Pediatrics, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison WI, USA
| | - Bruce S Klein
- Departments of Pediatrics, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison WI, USA; Departments of Internal Medicine, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison WI, USA; Departments of Medical Microbiology and Immunology, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison WI, USA.
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13
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Torres-Sánchez M, Villate J, McGrath-Blaser S, Longo AV. Panzootic chytrid fungus exploits diverse amphibian host environments through plastic infection strategies. Mol Ecol 2022; 31:4558-4570. [PMID: 35796691 DOI: 10.1111/mec.16601] [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: 12/20/2021] [Revised: 06/28/2022] [Accepted: 06/30/2022] [Indexed: 11/29/2022]
Abstract
While some pathogens are limited to single species, others can colonize many hosts, likely contributing to the emergence of novel disease outbreaks. Despite this biodiversity threat, traits associated with host niche expansions are not well understood in multi-host pathogens. Here, we aimed to uncover functional machinery driving multi-host invasion by focusing on Batrachochytrium dendrobatidis (Bd), a pathogen that infects the skin of hundreds of amphibians worldwide. We performed a meta-analysis of Bd gene expression using data from published infection experiments and newly generated profiles. We analyzed Bd transcriptomic landscapes across the skin of 14 host species, reconstructed Bd isolates phylogenetic relationships, and inferred the origin and evolutionary history of differentially expressed genes under a phylogenetic framework comprising other 12 zoosporic fungi. Bd displayed plastic infection strategies when challenged by hosts with different disease susceptibility. Our analyses identified sets of differentially expressed genes under host environments with similar infection outcome. We stressed nutritional immunity and gene silencing as important processes required to overcome challenging skin environments in less susceptible hosts. Overall, Bd genes expressed during amphibian skin exploitation have arisen mainly via gene duplications with great family expansions, increasing the gene copy events previously described for this fungal species. Finally, we provide a comprehensive gene dataset that can be used to further examine eco-evolutionary hypotheses for this host-pathogen system. Our study supports the idea that host environments exert contrasting selective pressures, such that gene expression plasticity could be one of the evolutionary keys leading to the success of multi-host pathogens.
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Affiliation(s)
| | - Jennifer Villate
- Department of Biology, University of Florida, 32611, Gainesville, FL
| | | | - Ana V Longo
- Department of Biology, University of Florida, 32611, Gainesville, FL
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14
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Martins RA, Greenspan SE, Medina D, Buttimer S, Marshall VM, Neely WJ, Siomko S, Lyra ML, Haddad CFB, São-Pedro V, Becker CG. Signatures of functional bacteriome structure in a tropical direct-developing amphibian species. Anim Microbiome 2022; 4:40. [PMID: 35672870 PMCID: PMC9172097 DOI: 10.1186/s42523-022-00188-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 05/17/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Host microbiomes may differ under the same environmental conditions and these differences may influence susceptibility to infection. Amphibians are ideal for comparing microbiomes in the context of disease defense because hundreds of species face infection with the skin-invading microbe Batrachochytrium dendrobatidis (Bd), and species richness of host communities, including their skin bacteria (bacteriome), may be exceptionally high. We conducted a landscape-scale Bd survey of six co-occurring amphibian species in Brazil’s Atlantic Forest. To test the bacteriome as a driver of differential Bd prevalence, we compared bacteriome composition and co-occurrence network structure among the six focal host species.
Results
Intensive sampling yielded divergent Bd prevalence in two ecologically similar terrestrial-breeding species, a group with historically low Bd resistance. Specifically, we detected the highest Bd prevalence in Ischnocnema henselii but no Bd detections in Haddadus binotatus. Haddadus binotatus carried the highest bacteriome alpha and common core diversity, and a modular network partitioned by negative co-occurrences, characteristics associated with community stability and competitive interactions that could inhibit Bd colonization.
Conclusions
Our findings suggest that community structure of the bacteriome might drive Bd resistance in H. binotatus, which could guide microbiome manipulation as a conservation strategy to protect diverse radiations of direct-developing species from Bd-induced population collapses.
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15
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Longo AV. Metabarcoding approaches in amphibian disease ecology: Disentangling the functional contributions of skin bacteria on disease outcome. Integr Comp Biol 2022; 62:252-261. [PMID: 35640913 DOI: 10.1093/icb/icac062] [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: 03/11/2022] [Revised: 05/10/2022] [Accepted: 05/25/2022] [Indexed: 01/09/2023] Open
Abstract
Molecular technologies have revolutionized the field of wildlife disease ecology, allowing the detection of outbreaks, novel pathogens, and invasive strains. In particular, metabarcoding approaches, defined here as tools used to amplify and sequence universal barcodes from a single sample (e.g., 16S rRNA for bacteria, ITS for fungi, 18S rRNA for eukaryotes), are expanding our traditional view of host-pathogen dynamics by integrating microbial interactions that modulate disease outcome. Here, I provide an analysis from the perspective of the field of amphibian disease ecology, where the emergence of multi-host pathogens has caused global declines and species extinctions. I re-analyzed an experimental mesocosm dataset to infer the functional profiles of the skin microbiomes of coqui frogs (Eleutherodactylus coqui), an amphibian species that is consistently found infected with the fungal pathogen Batrachochytrium dendrobatidis and has high turnover of skin bacteria driven by seasonal shifts. I found that the metabolic activities of microbiomes operate at different capacities depending on the season. Global enrichment of predicted functions was more prominent during the warm-wet season, indicating that microbiomes during the cool-dry season were either depauperate, resistant to new bacterial colonization, or that their functional space was more saturated. These findings suggest important avenues to investigate how microbes regulate population growth and contribute to host physiological processes. Overall, this study highlights the current challenges and future opportunities in the application of metabarcoding to investigate the causes and consequences of disease in wild systems.
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Affiliation(s)
- Ana V Longo
- University of Florida, Department of Biology, PO Box 118525, Gainesville, FL
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16
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Carlson KB, Wcisel DJ, Ackerman HD, Romanet J, Christiansen EF, Niemuth JN, Williams C, Breen M, Stoskopf MK, Dornburg A, Yoder JA. Transcriptome annotation reveals minimal immunogenetic diversity among Wyoming toads, Anaxyrus baxteri. CONSERV GENET 2022; 23:669-681. [PMID: 37090205 PMCID: PMC10118071 DOI: 10.1007/s10592-022-01444-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Briefly considered extinct in the wild, the future of the Wyoming toad (Anaxyrus baxteri) continues to rely on captive breeding to supplement the wild population. Given its small natural geographic range and history of rapid population decline at least partly due to fungal disease, investigation of the diversity of key receptor families involved in the host immune response represents an important conservation need. Population decline may have reduced immunogenetic diversity sufficiently to increase the vulnerability of the species to infectious diseases. Here we use comparative transcriptomics to examine the diversity of toll-like receptors and major histocompatibility complex (MHC) sequences across three individual Wyoming toads. We find reduced diversity at MHC genes compared to bufonid species with a similar history of bottleneck events. Our data provide a foundation for future studies that seek to evaluate the genetic diversity of Wyoming toads, identify biomarkers for infectious disease outcomes, and guide breeding strategies to increase genomic variability and wild release successes.
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Affiliation(s)
- Kara B. Carlson
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC, USA
| | - Dustin J. Wcisel
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC, USA
| | - Hayley D. Ackerman
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC, USA
| | - Jessica Romanet
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC, USA
| | - Emily F. Christiansen
- Environmental Medicine Consortium, North Carolina State University, Raleigh, NC, USA
- Department of Clinical Sciences, North Carolina State University, Raleigh, NC, USA
- North Carolina Aquariums, Raleigh, NC, USA
| | - Jennifer N. Niemuth
- Environmental Medicine Consortium, North Carolina State University, Raleigh, NC, USA
| | - Christina Williams
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC, USA
| | - Matthew Breen
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC, USA
- Comparative Medicine Institute, North Carolina State University, Raleigh, NC, USA
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, USA
| | - Michael K. Stoskopf
- Environmental Medicine Consortium, North Carolina State University, Raleigh, NC, USA
- Department of Clinical Sciences, North Carolina State University, Raleigh, NC, USA
| | - Alex Dornburg
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, Charlotte, NC USA
| | - Jeffrey A. Yoder
- Department of Molecular Biomedical Sciences, North Carolina State University, Raleigh, NC, USA
- Comparative Medicine Institute, North Carolina State University, Raleigh, NC, USA
- Center for Human Health and the Environment, North Carolina State University, Raleigh, NC, USA
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17
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Folly AJ, Marston DA, Golding M, Shukla S, Wilkie R, Lean FZX, Núñez A, Worledge L, Aegerter J, Banyard AC, Fooks AR, Johnson N, McElhinney LM. Incursion of European Bat Lyssavirus 1 (EBLV-1) in Serotine Bats in the United Kingdom. Viruses 2021; 13:v13101979. [PMID: 34696409 PMCID: PMC8536961 DOI: 10.3390/v13101979] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 09/29/2021] [Accepted: 09/29/2021] [Indexed: 11/16/2022] Open
Abstract
Lyssaviruses are an important genus of zoonotic viruses which cause the disease rabies. The United Kingdom is free of classical rabies (RABV). However, bat rabies due to European bat lyssavirus 2 (EBLV-2), has been detected in Daubenton’s bats (Myotis daubentonii) in Great Britain since 1996, including a fatal human case in Scotland in 2002. Across Europe, European bat lyssavirus 1 (EBLV-1) is commonly associated with serotine bats (Eptesicus serotinus). Despite the presence of serotine bats across large parts of southern England, EBLV-1 had not previously been detected in this population. However, in 2018, EBLV-1 was detected through passive surveillance in a serotine bat from Dorset, England, using a combination of fluorescent antibody test, reverse transcription-PCR, Sanger sequencing and immunohistochemical analysis. Subsequent EBLV-1 positive serotine bats have been identified in South West England, again through passive surveillance, during 2018, 2019 and 2020. Here, we confirm details of seven cases of EBLV-1 and present similarities in genetic sequence indicating that emergence of EBLV-1 is likely to be recent, potentially associated with the natural movement of bats from the near continent
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Affiliation(s)
- Arran J. Folly
- Virology Department, Animal and Plant Health Agency, Woodham Lane, Addlestone KT15 3NB, UK; (D.A.M.); (M.G.); (S.S.); (R.W.); (A.C.B.); (A.R.F.); (N.J.); (L.M.M.)
- Correspondence:
| | - Denise A. Marston
- Virology Department, Animal and Plant Health Agency, Woodham Lane, Addlestone KT15 3NB, UK; (D.A.M.); (M.G.); (S.S.); (R.W.); (A.C.B.); (A.R.F.); (N.J.); (L.M.M.)
| | - Megan Golding
- Virology Department, Animal and Plant Health Agency, Woodham Lane, Addlestone KT15 3NB, UK; (D.A.M.); (M.G.); (S.S.); (R.W.); (A.C.B.); (A.R.F.); (N.J.); (L.M.M.)
| | - Shweta Shukla
- Virology Department, Animal and Plant Health Agency, Woodham Lane, Addlestone KT15 3NB, UK; (D.A.M.); (M.G.); (S.S.); (R.W.); (A.C.B.); (A.R.F.); (N.J.); (L.M.M.)
| | - Rebekah Wilkie
- Virology Department, Animal and Plant Health Agency, Woodham Lane, Addlestone KT15 3NB, UK; (D.A.M.); (M.G.); (S.S.); (R.W.); (A.C.B.); (A.R.F.); (N.J.); (L.M.M.)
| | - Fabian Z. X. Lean
- Pathology and Animal Sciences Department, Animal and Plant Health Agency, Addlestone KT15 3NB, UK; (F.Z.X.L.); (A.N.)
| | - Alejandro Núñez
- Pathology and Animal Sciences Department, Animal and Plant Health Agency, Addlestone KT15 3NB, UK; (F.Z.X.L.); (A.N.)
| | - Lisa Worledge
- Bat Conservation Trust, Studio 15 Cloisters House, Cloisters Business Centre, 8 Battersea Park Road, London SW8 4BG, UK;
| | - James Aegerter
- National Wildlife Management Centre, Animal and Plant Health Agency, Sand Hutton, York YO41 1LZ, UK;
| | - Ashley C. Banyard
- Virology Department, Animal and Plant Health Agency, Woodham Lane, Addlestone KT15 3NB, UK; (D.A.M.); (M.G.); (S.S.); (R.W.); (A.C.B.); (A.R.F.); (N.J.); (L.M.M.)
| | - Anthony R. Fooks
- Virology Department, Animal and Plant Health Agency, Woodham Lane, Addlestone KT15 3NB, UK; (D.A.M.); (M.G.); (S.S.); (R.W.); (A.C.B.); (A.R.F.); (N.J.); (L.M.M.)
| | - Nicholas Johnson
- Virology Department, Animal and Plant Health Agency, Woodham Lane, Addlestone KT15 3NB, UK; (D.A.M.); (M.G.); (S.S.); (R.W.); (A.C.B.); (A.R.F.); (N.J.); (L.M.M.)
| | - Lorraine M. McElhinney
- Virology Department, Animal and Plant Health Agency, Woodham Lane, Addlestone KT15 3NB, UK; (D.A.M.); (M.G.); (S.S.); (R.W.); (A.C.B.); (A.R.F.); (N.J.); (L.M.M.)
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18
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Eskew EA, Fraser D, Vonhof MJ, Pinsky ML, Maslo B. Host gene expression in wildlife disease: making sense of species-level responses. Mol Ecol 2021; 30:6517-6530. [PMID: 34516689 DOI: 10.1111/mec.16172] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 08/16/2021] [Accepted: 08/31/2021] [Indexed: 12/11/2022]
Abstract
Emerging infectious diseases are significant threats to wildlife conservation, yet the impacts of pathogen exposure and infection can vary widely among host species. As such, conservation biologists and disease ecologists have increasingly aimed to understand species-specific host susceptibility using molecular methods. In particular, comparative gene expression assays have been used to contrast the transcriptomic responses of disease-resistant and disease-susceptible hosts to pathogen exposure. This work usually assumes that the gene expression responses of disease-resistant species will reveal the activation of molecular pathways contributing to host defence. However, results often show that disease-resistant hosts undergo little gene expression change following pathogen challenge. Here, we discuss the mechanistic implications of these "null" findings and offer methodological suggestions for future molecular studies of wildlife disease. First, we highlight that muted transcriptomic responses with minimal immune system recruitment may indeed be protective for nonsusceptible hosts if they limit immunopathology and promote pathogen tolerance in systems where susceptible hosts suffer from genetic dysregulation. Second, we argue that overly narrow investigation of responses to pathogen exposure may overlook important, constitutively active molecular pathways that underlie species-specific defences. Finally, we outline alternative study designs and approaches that complement interspecific transcriptomic comparisons, including intraspecific gene expression studies and genomic methods to detect signatures of selection. Collectively, these insights will help ecologists extract maximal information from conservation-relevant transcriptomic data sets, leading to a deeper understanding of host defences and, ultimately, the implementation of successful conservation interventions.
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Affiliation(s)
- Evan A Eskew
- Department of Ecology, Evolution and Natural Resources, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA.,Department of Biology, Pacific Lutheran University, Tacoma, Washington, USA
| | - Devaughn Fraser
- Wildlife Genetics Research Laboratory, California Department of Fish and Wildlife, Sacramento, California, USA
| | - Maarten J Vonhof
- Department of Biological Sciences, Western Michigan University, Kalamazoo, Michigan, USA
| | - Malin L Pinsky
- Department of Ecology, Evolution and Natural Resources, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA
| | - Brooke Maslo
- Department of Ecology, Evolution and Natural Resources, Rutgers, The State University of New Jersey, New Brunswick, New Jersey, USA
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19
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Tobias ZJC, Fowler AE, Blakeslee AMH, Darling JA, Torchin ME, Miller AW, Ruiz GM, Tepolt CK. Invasion history shapes host transcriptomic response to a body-snatching parasite. Mol Ecol 2021; 30:4321-4337. [PMID: 34162013 PMCID: PMC10128110 DOI: 10.1111/mec.16038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 05/27/2021] [Accepted: 06/11/2021] [Indexed: 01/04/2023]
Abstract
By shuffling biogeographical distributions, biological invasions can both disrupt long-standing associations between hosts and parasites and establish new ones. This creates natural experiments with which to study the ecology and evolution of host-parasite interactions. In estuaries of the Gulf of Mexico, the white-fingered mud crab (Rhithropanopeus harrisii) is infected by a native parasitic barnacle, Loxothylacus panopaei (Rhizocephala), which manipulates host physiology and behaviour. In the 1960s, L. panopaei was introduced to the Chesapeake Bay and has since expanded along the southeastern Atlantic coast, while host populations in the northeast have so far been spared. We use this system to test the host's transcriptomic response to parasitic infection and investigate how this response varies with the parasite's invasion history, comparing populations representing (i) long-term sympatry between host and parasite, (ii) new associations where the parasite has invaded during the last 60 years and (iii) naïve hosts without prior exposure. A comparison of parasitized and control crabs revealed a core response, with widespread downregulation of transcripts involved in immunity and moulting. The transcriptional response differed between hosts from the parasite's native range and where it is absent, consistent with previous observations of increased susceptibility in populations lacking exposure to the parasite. Crabs from the parasite's introduced range, where prevalence is highest, displayed the most dissimilar response, possibly reflecting immune priming. These results provide molecular evidence for parasitic manipulation of host phenotype and the role of gene regulation in mediating host-parasite interactions.
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Affiliation(s)
- Zachary J C Tobias
- MIT-WHOI Joint Program in Oceanography/Applied Ocean Science and Engineering, Cambridge and Woods Hole, MA, USA.,Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.,Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Amy E Fowler
- Department of Environmental Science and Policy, George Mason University, Fairfax, VA, USA
| | | | - John A Darling
- National Exposure Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Mark E Torchin
- Smithsonian Tropical Research Institute, Balboa, Ancon, Republic of Panama
| | | | - Gregory M Ruiz
- Smithsonian Environmental Research Center, Edgewater, MD, USA
| | - Carolyn K Tepolt
- Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.,Smithsonian Environmental Research Center, Edgewater, MD, USA
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20
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Rollins-Smith LA, Le Sage EH. Batrachochytrium fungi: stealth invaders in amphibian skin. Curr Opin Microbiol 2021; 61:124-132. [PMID: 33964650 DOI: 10.1016/j.mib.2021.04.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/07/2021] [Accepted: 04/15/2021] [Indexed: 10/21/2022]
Abstract
Amphibian populations around the world have been affected by two pathogenic fungi within the phylum Chytridiomycota. Batrachochytrium dendrobatidis (Bd) has infected hundreds of species and led to widespread declines and some species extinctions. Batrachochytrium salamandrivorans (Bsal) has devastated some native European salamanders, especially the iconic fire salamanders (Salamandra salamandra). Comparative genomic studies show that Bd is more diverse and widespread than previously thought, and global lineages occur together allowing for the development of hybrid lineages. New studies raise the concern of greater pathogenesis if both Bd and Bsal infect the same host. Although amphibians possess robust immune defenses, co-infected and many single-infected hosts seem unable to mount effective immune responses. A strong defense may actually be harmful. Analysis of Bd and Bsal secretions documents small metabolites that signal high density to limit their growth and to suppress adaptive immune defenses, thus enabling a stealth presence in the skin compartment.
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Affiliation(s)
- Louise A Rollins-Smith
- Departments of Pathology, Microbiology and Immunology and of Pediatrics, Vanderbilt University School of Medicine and Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
| | - Emily H Le Sage
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
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21
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Byrne AQ, Richards-Zawacki CL, Voyles J, Bi K, Ibáñez R, Rosenblum EB. Whole exome sequencing identifies the potential for genetic rescue in iconic and critically endangered Panamanian harlequin frogs. GLOBAL CHANGE BIOLOGY 2021; 27:50-70. [PMID: 33150627 DOI: 10.1111/gcb.15405] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 09/24/2020] [Accepted: 10/02/2020] [Indexed: 06/11/2023]
Abstract
Avoiding extinction in a rapidly changing environment often relies on a species' ability to quickly adapt in the face of extreme selective pressures. In Panamá, two closely related harlequin frog species (Atelopus varius and Atelopus zeteki) are threatened with extinction due to the fungal pathogen Batrachochytrium dendrobatidis (Bd). Once thought to be nearly extirpated from Panamá, A. varius have recently been rediscovered in multiple localities across their historical range; however, A. zeteki are possibly extinct in the wild. By leveraging a unique collection of 186 Atelopus tissue samples collected before and after the Bd outbreak in Panama, we describe the genetics of persistence for these species on the brink of extinction. We sequenced the transcriptome and developed an exome-capture assay to sequence the coding regions of the Atelopus genome. Using these genetic data, we evaluate the population genetic structure of historical A. varius and A. zeteki populations, describe changes in genetic diversity over time, assess the relationship between contemporary and historical individuals, and test the hypothesis that some A. varius populations have rapidly evolved to resist or tolerate Bd infection. We found a significant decrease in genetic diversity in contemporary (compared to historical) A. varius populations. We did not find strong evidence of directional allele frequency change or selection for Bd resistance genes, but we uncovered a set of candidate genes that warrant further study. Additionally, we found preliminary evidence of recent migration and gene flow in one of the largest persisting A. varius populations in Panamá, suggesting the potential for genetic rescue in this system. Finally, we propose that previous conservation units should be modified, as clear genetic breaks do not exist beyond the local population level. Our data lay the groundwork for genetically informed conservation and advance our understanding of how imperiled species might be rescued from extinction.
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Affiliation(s)
- Allison Q Byrne
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, USA
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA
| | | | - Jamie Voyles
- Department of Biology, University of Nevada Reno, Reno, NV, USA
| | - Ke Bi
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA
| | - Roberto Ibáñez
- Smithsonian Tropical Research Institute, Panamá, República de Panamá
- Sistema Nacional de Investigación, SENACYT, Clayton, Panamá, República de Panamá
| | - Erica Bree Rosenblum
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, USA
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA
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22
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Grogan LF, Humphries JE, Robert J, Lanctôt CM, Nock CJ, Newell DA, McCallum HI. Immunological Aspects of Chytridiomycosis. J Fungi (Basel) 2020; 6:jof6040234. [PMID: 33086692 PMCID: PMC7712659 DOI: 10.3390/jof6040234] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 12/27/2022] Open
Abstract
Amphibians are currently the most threatened vertebrate class, with the disease chytridiomycosis being a major contributor to their global declines. Chytridiomycosis is a frequently fatal skin disease caused by the fungal pathogens Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal). The severity and extent of the impact of the infection caused by these pathogens across modern Amphibia are unprecedented in the history of vertebrate infectious diseases. The immune system of amphibians is thought to be largely similar to that of other jawed vertebrates, such as mammals. However, amphibian hosts are both ectothermic and water-dependent, which are characteristics favouring fungal proliferation. Although amphibians possess robust constitutive host defences, Bd/Bsal replicate within host cells once these defences have been breached. Intracellular fungal localisation may contribute to evasion of the induced innate immune response. Increasing evidence suggests that once the innate defences are surpassed, fungal virulence factors suppress the targeted adaptive immune responses whilst promoting an ineffectual inflammatory cascade, resulting in immunopathology and systemic metabolic disruption. Thus, although infections are contained within the integument, crucial homeostatic processes become compromised, leading to mortality. In this paper, we present an integrated synthesis of amphibian post-metamorphic immunological responses and the corresponding outcomes of infection with Bd, focusing on recent developments within the field and highlighting future directions.
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Affiliation(s)
- Laura F. Grogan
- Environmental Futures Research Institute and School of Environment and Science, Griffith University, Southport, QLD 4222, Australia;
- Forest Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW 2480, Australia; (J.E.H.); (D.A.N.)
- Correspondence:
| | - Josephine E. Humphries
- Forest Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW 2480, Australia; (J.E.H.); (D.A.N.)
| | - Jacques Robert
- University of Rochester Medical Center, Rochester, NY 14642, USA;
| | - Chantal M. Lanctôt
- Australian Rivers Institute, Griffith University, Southport, QLD 4222, Australia;
| | - Catherine J. Nock
- Southern Cross Plant Science, Southern Cross University, Lismore, NSW 2480, Australia;
| | - David A. Newell
- Forest Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW 2480, Australia; (J.E.H.); (D.A.N.)
| | - Hamish I. McCallum
- Environmental Futures Research Institute and School of Environment and Science, Griffith University, Southport, QLD 4222, Australia;
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