1
|
Rollins-Smith LA. The future of amphibian immunology: Opportunities and challenges. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2024; 160:105237. [PMID: 39103004 DOI: 10.1016/j.dci.2024.105237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2024] [Revised: 07/19/2024] [Accepted: 08/02/2024] [Indexed: 08/07/2024]
Abstract
Historically, amphibians have been essential to our understanding of vertebrate biology and animal development. Because development from egg to tadpole to adult frog can be directly observed, amphibians contributed greatly to our understanding of not only vertebrate animal development but also the development of the immune system. The South African clawed frog (Xenopus laevis) has been key to many of these findings. For example, using Xenopus as a model, the comparative immunology community learned about the contribution of hematopoietic stem cells to development of the immune system and about the diversity of antibodies, B cells, T cells and antigen presenting cells. Amphibians offer many advantages as unique potential model systems to address questions about immune skin interactions, host responses to mycobacteria, the diverse functions of interferons, and immune and mucosal interactions. However, there are also many challenges to advance the research including the lack of specific reagents and well annotated genomes of diverse species. While much is known, many important questions remain. The aim of this short commentary is to look to the future of comparative immunology of amphibians as a group. By identifying some important questions or "information-deficit" areas of research, I hope to pique the interest of younger developing scientists and persuade funding agencies to continue to support comparative immunology studies including those of amphibians.
Collapse
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.
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
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: 6] [Impact Index Per Article: 6.0] [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'.
Collapse
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
| |
Collapse
|
4
|
Crim MJ, Hart ML. Health Monitoring for Laboratory Salamanders. Methods Mol Biol 2023; 2562:41-74. [PMID: 36272067 DOI: 10.1007/978-1-0716-2659-7_3] [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] [Indexed: 06/16/2023]
Abstract
Laboratory animal health monitoring programs are necessary to protect animal health and welfare, the validity of experimental data, and human health against zoonotic infections. Health monitoring programs should be designed based on a risk assessment and knowledge about the biology and transmission of salamander pathogens. Both traditional and molecular diagnostic platforms are available for salamanders, and they provide complementary information. A comprehensive approach to health monitoring leverages the advantages of multiple platforms to provide a more complete picture of colony health and pathogen status. This chapter presents key considerations in the design and implementation of a colony health monitoring program for laboratory salamanders, including protocols for necropsy and sample collection.
Collapse
|
5
|
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: 8] [Impact Index Per Article: 4.0] [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.
Collapse
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
| |
Collapse
|
6
|
Coinfection of Chytrid Fungi in Urodeles during an Outbreak of Chytridiomycosis in Spain. J Wildl Dis 2022; 58:658-663. [PMID: 35666851 DOI: 10.7589/jwd-d-21-00170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 03/03/2022] [Indexed: 11/20/2022]
Abstract
Chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal), has had an unprecedented impact on amphibian biodiversity. Although Bd is globally widespread, Bsal is currently spreading, increasing the probability that these pathogens will co-occur in individual amphibians. Interactions among coinfecting parasites can have significant outcomes on disease dynamics and impact and, therefore, may have important consequences for amphibian conservation. We analyzed the patterns of Bd-Bsal coinfections in two species of free-ranging urodeles during an outbreak of chytridiomycosis in Spain. Our goals were to assess 1) the probability of co-occurrence of both chytrid species and 2) the correlation of pathogen loads in coinfected hosts. We detected coinfections in 81.58% of Triturus marmoratus (n=38) and in 18.75% of Ichthyosaura alpestris (n=16). Histopathologic lesions of chytridiomycosis were observed only in T. marmoratus. Our results demonstrate a positive relationship between Bd and Bsal loads in T. marmoratus, whereas the co-occurrence analysis showed a random association among pathogens in both urodele species. Overall, we show that Bd-Bsal coinfections intensify pathogen load in T. marmoratus and could, therefore, increase disease severity and have important consequences for the conservation of some amphibian species.
Collapse
|
7
|
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.
Collapse
Affiliation(s)
- Ana V Longo
- University of Florida, Department of Biology, PO Box 118525, Gainesville, FL
| |
Collapse
|
8
|
Lymphocyte Inhibition by the Salamander-Killing Chytrid Fungus, Batrachochytrium salamandrivorans. Infect Immun 2022; 90:e0002022. [PMID: 35130454 PMCID: PMC8929357 DOI: 10.1128/iai.00020-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Amphibian populations have been declining around the world for more than five decades, and the losses continue. Although causes are complex, major contributors to these declines are two chytrid fungi, Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans, which both cause the disease termed chytridiomycosis. Previously, we showed that B. dendrobatidis impedes amphibian defenses by directly inhibiting lymphocytes in vitro and in vivo by release of soluble metabolites, including kynurenine (KYN), methylthioadenosine (MTA), and spermidine (SPD). Here, we show that B. salamandrivorans cells and cell-free supernatants also inhibit amphibian lymphocytes as well as a human T cell line. As we have shown for B. dendrobatidis, high-performance liquid chromatography (HPLC) and mass spectrometry revealed that KYN, MTA, and SPD are key metabolites found in the B. salamandrivorans supernatants. Production of inhibitory factors by B. salamandrivorans is limited to mature zoosporangia and can occur over a range of temperatures between 16°C and 26°C. Taken together, these results suggest that both pathogenic Batrachochytrium fungi have evolved similar mechanisms to inhibit lymphocytes in order to evade clearance by the amphibian immune system.
Collapse
|
9
|
García‐Rodríguez A, Basanta MD, García‐Castillo MG, Zumbado‐Ulate H, Neam K, Rovito S, Searle CL, Parra‐Olea G. Anticipating the potential impacts of
Batrachochytrium salamandrivorans
on Neotropical salamander diversity. Biotropica 2021. [DOI: 10.1111/btp.13042] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Adrián García‐Rodríguez
- Departamento de Zoología Instituto de Biología Universidad Nacional Autónoma de México Ciudad de México México
- BioInvasions, Global Change, Macroecology‐Group Department of Botany and Biodiversity Research University of Vienna Vienna Austria
| | - M. Delia Basanta
- Departamento de Zoología Instituto de Biología Universidad Nacional Autónoma de México Ciudad de México México
- Centro de Ciencias Genómicas Universidad Nacional Autónoma de México Cuernavaca Morelos México
| | - Mirna G. García‐Castillo
- Universidad Politécnica de Huatusco Huatusco Veracruz México
- Facultad de Ciencias Biológicas y Agropecuarias Región: Orizaba–Córdoba Universidad Veracruzana Amatlán de los Reyes Veracruz México
| | | | - Kelsey Neam
- Global Wildlife Conservation Austin Texas USA
- Amphibian Specialist Group IUCN Species Survival Commission USA
| | - Sean Rovito
- Unidad de Genómica Avanzada (Langebio) CINVESTAV Irapuato México
| | - Catherine L. Searle
- Department of Biological Sciences Purdue University West Lafayette Indiana USA
| | - Gabriela Parra‐Olea
- Departamento de Zoología Instituto de Biología Universidad Nacional Autónoma de México Ciudad de México México
- Amphibian Specialist Group IUCN Species Survival Commission USA
| |
Collapse
|
10
|
Early-diverging fungal phyla: taxonomy, species concept, ecology, distribution, anthropogenic impact, and novel phylogenetic proposals. FUNGAL DIVERS 2021; 109:59-98. [PMID: 34608378 PMCID: PMC8480134 DOI: 10.1007/s13225-021-00480-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Accepted: 07/19/2021] [Indexed: 01/02/2023]
Abstract
The increasing number of new fungal species described from all over the world along with the use of genetics to define taxa, has dramatically changed the classification system of early-diverging fungi over the past several decades. The number of phyla established for non-Dikarya fungi has increased from 2 to 17. However, to date, both the classification and phylogeny of the basal fungi are still unresolved. In this article, we review the recent taxonomy of the basal fungi and re-evaluate the relationships among early-diverging lineages of fungal phyla. We also provide information on the ecology and distribution in Mucoromycota and highlight the impact of chytrids on amphibian populations. Species concepts in Chytridiomycota, Aphelidiomycota, Rozellomycota, Neocallimastigomycota are discussed in this paper. To preserve the current application of the genus Nephridiophaga (Chytridiomycota: Nephridiophagales), a new type species, Nephridiophaga blattellae, is proposed.
Collapse
|
11
|
Sweeny AR, Albery GF, Becker DJ, Eskew EA, Carlson CJ. Synzootics. J Anim Ecol 2021; 90:2744-2754. [PMID: 34546566 DOI: 10.1111/1365-2656.13595] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 09/14/2021] [Indexed: 12/30/2022]
Abstract
Ecologists increasingly recognise coinfection as an important component of emergent epidemiological patterns, connecting aspects of ecoimmunology, behaviour, ecosystem function and even extinction risk. Building on syndemic theory in medical anthropology, we propose the term 'synzootics' to describe co-occurring enzootic or epizootic processes that produce worse health outcomes in wild animals. Using framing from syndemic theory, we describe how the synzootic concept offers new insights into the ecology and evolution of infectious diseases. We then recommend a set of empirical criteria and lines of evidence that can be used to identify synzootics in nature. We conclude by exploring how synzootics could indirectly drive the emergence of novel pathogens in human populations.
Collapse
Affiliation(s)
- Amy R Sweeny
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, UK
| | - Gregory F Albery
- Department of Biology, Georgetown University, Washington, District of Columbia, USA
| | - Daniel J Becker
- Department of Biology, University of Oklahoma, Norman, Oklahoma, USA
| | - Evan A Eskew
- Department of Biology, Pacific Lutheran University, Tacoma, Washington, USA
| | - Colin J Carlson
- Center for Global Health Science and Security, Georgetown University Medical Center, Georgetown University, Washington, District of Columbia, USA
| |
Collapse
|
12
|
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: 9] [Impact Index Per Article: 3.0] [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.
Collapse
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
| |
Collapse
|
13
|
Boys IN, Mar KB, Schoggins JW. Functional-genomic analysis reveals intraspecies diversification of antiviral receptor transporter proteins in Xenopus laevis. PLoS Genet 2021; 17:e1009578. [PMID: 34014925 PMCID: PMC8172065 DOI: 10.1371/journal.pgen.1009578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 06/02/2021] [Accepted: 05/04/2021] [Indexed: 12/05/2022] Open
Abstract
The Receptor Transporter Protein (RTP) family is present in most, if not all jawed vertebrates. Most of our knowledge of this protein family comes from studies on mammalian RTPs, which are multi-function proteins that regulate cell-surface G-protein coupled receptor levels, influence olfactory system development, regulate immune signaling, and directly inhibit viral infection. However, mammals comprise less than one-tenth of extant vertebrate species, and our knowledge about the expression, function, and evolution of non-mammalian RTPs is limited. Here, we explore the evolutionary history of RTPs in vertebrates. We identify signatures of positive selection in many vertebrate RTP clades and characterize multiple, independent expansions of the RTP family outside of what has been described in mammals. We find a striking expansion of RTPs in the African clawed frog, Xenopus laevis, with 11 RTPs in this species as opposed to 1 to 4 in most other species. RNA sequencing revealed that most X. laevis RTPs are upregulated following immune stimulation. In functional assays, we demonstrate that at least three of these X. laevis RTPs inhibit infection by RNA viruses, suggesting that RTP homologs may serve as antiviral effectors outside of Mammalia.
Collapse
Affiliation(s)
- Ian N. Boys
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Katrina B. Mar
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - John W. Schoggins
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| |
Collapse
|
14
|
Rieseberg L, Warschefsky E, O’Boyle B, Taberlet P, Ortiz‐Barrientos D, Kane NC, Sibbett B. Editorial 2021. Mol Ecol 2020. [DOI: 10.1111/mec.15759] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
15
|
Friday B, Holzheuser C, Lips KR, Longo AV. Preparing for invasion: Assessing risk of infection by chytrid fungi in southeastern plethodontid salamanders. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2020; 333:829-840. [PMID: 33174393 DOI: 10.1002/jez.2427] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 09/30/2020] [Accepted: 10/23/2020] [Indexed: 12/31/2022]
Abstract
Understanding the responses of naïve communities to the invasion of multihost pathogens requires accurate estimates of susceptibility across taxa. In the Americas, the likely emergence of a second amphibian pathogenic fungus (Batrachochytrium salamandrivorans, Bsal) calls for new ways of prioritizing disease mitigation among species due to the high diversity of naïve hosts with prior B. dendrobatidis (Bd) infections. Here, we applied the concept of pathogenic potential to quantify the virulence of chytrid fungi on naïve amphibians and evaluate species for conservation efforts in the event of an outbreak. The benefit of this measure is that it combines and summarizes the variation in disease effects into a single numerical index, allowing for comparisons across species, populations or groups of individuals that may inherently exhibit differences in susceptibility. As a proof of concept, we obtained standardized responses of disease severity by performing experimental infections with Bsal on five plethodontid salamanders from southeastern United States. Four out of five species carried natural infections of Bd at the start of the experiments. We showed that Bsal exhibited its highest value of pathogenic potential in a species that is already declining (Desmognathus auriculatus). We find that this index provides additional information beyond the standard measures of disease prevalence, intensity, and mortality, because it leveraged these disease parameters within each categorical group. Scientists and practitioners could use this measure to justify research, funding, trade, or conservation measures.
Collapse
Affiliation(s)
- Brenna Friday
- Department of Biology, University of Maryland, College Park, Maryland, USA.,Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Chace Holzheuser
- Department of Biology, University of Maryland, College Park, Maryland, USA.,Department of Biological Science, Florida State University, Tallahassee, Florida, USA
| | - Karen R Lips
- Department of Biology, University of Maryland, College Park, Maryland, USA
| | - Ana V Longo
- Department of Biology, University of Florida, Gainesville, Florida, USA
| |
Collapse
|
16
|
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: 21] [Impact Index Per Article: 5.3] [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.
Collapse
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;
| |
Collapse
|
17
|
Shepack A, Catenazzi A. Transcriptomics reveal immune downregulation of newts overwhelmed by chytrid co-infection. Mol Ecol 2020; 29:3167-3169. [PMID: 32745298 DOI: 10.1111/mec.15576] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 07/27/2020] [Indexed: 12/11/2022]
Abstract
What happens when two emergent diseases infect the same host? In a From the Cover article in this issue of Molecular Ecology, McDonald et al. (2020) compare transcriptomic responses to co-infection by the two chytrid fungi in the skin, liver and spleen of Eastern newts (Notophthalmus viridescens). Novel molecular tools, such as high-throughput DNA sequencing for genome discovery and transcriptomics, have revolutionized our understanding of host-pathogen interactions and disease ecology (Güimil et al. 2005; Rosenblum et al. 2012). For example, epidemiologists are using genomic data to track the spread of the emergent SARS-CoV-2 in real time, both locally and globally. RNA sequencing (RNA-Seq) is routinely employed to study response to disease in humans, improving disease diagnostics, profiling and development of intervention strategies. Transcriptomic profiles may be particularly informative for emergent diseases, whose pathologies and effect on host phenotype are poorly known. Fungal pathogens increasingly threaten a variety of wild and domesticated organisms (Fisher et al. 2012), and two chytrid fungi attacking amphibians are causing one of the worst losses of vertebrate biodiversity ever recorded (Scheele et al. 2019).
Collapse
Affiliation(s)
- Alexander Shepack
- Department of Biological Sciences, Florida International University, Miami, FL, USA
| | - Alessandro Catenazzi
- Department of Biological Sciences, Florida International University, Miami, FL, USA
| |
Collapse
|
18
|
Zamudio KR, McDonald CA, Belasen AM. High Variability in Infection Mechanisms and Host Responses: A Review of Functional Genomic Studies of Amphibian Chytridiomycosis. HERPETOLOGICA 2020. [DOI: 10.1655/0018-0831-76.2.189] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Kelly R. Zamudio
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853-2701, USA
| | - Cait A. McDonald
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853-2701, USA
| | - Anat M. Belasen
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853-2701, USA
| |
Collapse
|