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Waddle AW, Clulow S, Aquilina A, Sauer EL, Kaiser SW, Miller C, Flegg JA, Campbell PT, Gallagher H, Dimovski I, Lambreghts Y, Berger L, Skerratt LF, Shine R. Hotspot shelters stimulate frog resistance to chytridiomycosis. Nature 2024:10.1038/s41586-024-07582-y. [PMID: 38926575 DOI: 10.1038/s41586-024-07582-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 05/17/2024] [Indexed: 06/28/2024]
Abstract
Many threats to biodiversity cannot be eliminated; for example, invasive pathogens may be ubiquitous. Chytridiomycosis is a fungal disease that has spread worldwide, driving at least 90 amphibian species to extinction, and severely affecting hundreds of others1-4. Once the disease spreads to a new environment, it is likely to become a permanent part of that ecosystem. To enable coexistence with chytridiomycosis in the field, we devised an intervention that exploits host defences and pathogen vulnerabilities. Here we show that sunlight-heated artificial refugia attract endangered frogs and enable body temperatures high enough to clear infections, and that having recovered in this way, frogs are subsequently resistant to chytridiomycosis even under cool conditions that are optimal for fungal growth. Our results provide a simple, inexpensive and widely applicable strategy to buffer frogs against chytridiomycosis in nature. The refugia are immediately useful for the endangered species we tested and will have broader utility for amphibian species with similar ecologies. Furthermore, our concept could be applied to other wildlife diseases in which differences in host and pathogen physiologies can be exploited. The refugia are made from cheap and readily available materials and therefore could be rapidly adopted by wildlife managers and the public. In summary, habitat protection alone cannot protect species that are affected by invasive diseases, but simple manipulations to microhabitat structure could spell the difference between the extinction and the persistence of endangered amphibians.
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Affiliation(s)
- Anthony W Waddle
- Melbourne Veterinary School, University of Melbourne, Werribee, Victoria, Australia.
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia.
- Applied BioSciences, Macquarie University, Sydney, New South Wales, Australia.
| | - Simon Clulow
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
- Centre for Conservation Ecology and Genomics, Institute for Applied Ecology, University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Amy Aquilina
- Melbourne Veterinary School, University of Melbourne, Werribee, Victoria, Australia
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Erin L Sauer
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA
| | - Shannon W Kaiser
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Claire Miller
- School of Mathematics and Statistics, University of Melbourne, Parkville, Victoria, Australia
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Jennifer A Flegg
- School of Mathematics and Statistics, University of Melbourne, Parkville, Victoria, Australia
| | - Patricia T Campbell
- Department of Infectious Diseases, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Harrison Gallagher
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Ivana Dimovski
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Yorick Lambreghts
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
- School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia
| | - Lee Berger
- Melbourne Veterinary School, University of Melbourne, Werribee, Victoria, Australia
| | - Lee F Skerratt
- Melbourne Veterinary School, University of Melbourne, Werribee, Victoria, Australia
| | - Richard Shine
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
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2
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Hawley L, Smalling KL, Glaberman S. Critical review of the phytohemagglutinin assay for assessing amphibian immunity. CONSERVATION PHYSIOLOGY 2023; 11:coad090. [PMID: 38090122 PMCID: PMC10714196 DOI: 10.1093/conphys/coad090] [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: 02/28/2023] [Revised: 09/15/2023] [Accepted: 10/26/2023] [Indexed: 04/26/2024]
Abstract
Infectious diseases are a major driver of the global amphibian decline. In addition, many factors, including genetics, stress, pollution, and climate change can influence the response to pathogens. Therefore, it is important to be able to evaluate amphibian immunity in the laboratory and in the field. The phytohemagglutinin (PHA) assay is an inexpensive and relatively non-invasive tool that has been used extensively to assess immunocompetence, especially in birds, and more recently in amphibians. However, there is substantial variation in experimental methodology among amphibian PHA studies in terms of species and life stages, PHA doses and injection sites, and use of experimental controls. Here, we compile and compare all known PHA studies in amphibians to identify knowledge gaps and develop best practices for future work. We found that research has only been conducted on a limited number of species, which may not reflect the diversity of amphibians. There is also a lack of validation studies in most species, so that doses and timing of PHA injection and subsequent swelling measurements may not effectively evaluate immunocompetence. Based on these and other findings, we put forward a set of recommendations to make future PHA studies more consistent and improve the ability to utilize this assay in wild populations, where immune surveillance is greatly needed.
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Affiliation(s)
- Lauren Hawley
- Department of Environmental Science and Policy, George Mason University, Fairfax, VA, USA
| | - Kelly L Smalling
- New Jersey Water Science Center, U.S. Geological Survey, Lawrenceville, NJ, USA
| | - Scott Glaberman
- Department of Environmental Science and Policy, George Mason University, Fairfax, VA, USA
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3
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Roth SA, Griffis-Kyle KL, Barnes MA. Batrachochytrium dendrobatidis in the Arid and Thermally Extreme Sonoran Desert. ECOHEALTH 2023; 20:370-380. [PMID: 38243042 DOI: 10.1007/s10393-023-01668-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 12/08/2023] [Indexed: 01/21/2024]
Abstract
Batrachochytrium dendrobatidis (Bd), the causative agent of the devastating global amphibian disease chytridiomycosis, was not projected to threaten amphibians in hot and arid regions due to its sensitivity to heat and desiccation. However, Bd is being detected more frequently than ever in hot and arid regions of Australia and the USA, challenging our current understanding of the environmental tolerances of the pathogen under natural conditions. We surveyed for Bd in an extremely hot and arid portion of the Sonoran Desert, where the pathogen is not projected to occur, and related presence and prevalence of the pathogen to local environmental conditions. We collected eDNA samples from isolated desert water sites including six tinajas and 13 catchments in June and August of 2020 and swabbed a total of 281 anurans of three species (red-spotted toad Anaxyrus punctatus, Couch's spadefoot Scaphiopus couchii, and the Sonoran Desert toad Incillius alvarius) across five catchments and six tinajas from June to September of 2020. Overall, Bd occurred at 68.4% of sites, despite extreme heat and aridity routinely exceeding tolerances established in laboratory studies. Average summer maximum air and water temperatures were 40.7°C and 30.7°C, respectively, and sites received an average of just 16.9 mm of precipitation throughout the summer monsoon season. Prevalence was low (5.7%) across species and life stage. Our results demonstrate that Bd is capable of persisting and infecting amphibians beyond its projected range, indicating a need to account for higher thermal tolerances when quantifying risk of Bd presence and infection.
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Affiliation(s)
- Sadie A Roth
- Department of Natural Resources Management, Texas Tech University, 2500 Broadway, Lubbock, TX, 79409, USA.
| | - Kerry L Griffis-Kyle
- Department of Natural Resources Management, Texas Tech University, 2500 Broadway, Lubbock, TX, 79409, USA
| | - Matthew A Barnes
- Department of Natural Resources Management, Texas Tech University, 2500 Broadway, Lubbock, TX, 79409, USA
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4
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Kendall MW, Wright AD, Adamovicz LA, Durante K, Andersson KE, Frederickson K, Vivirito K, Ospina EA, Delaney MA, Allender MC. Environmental temperature influences ophidiomycosis progression and survival in experimentally challenged prairie rattlesnakes (Crotalus viridis). PLoS One 2023; 18:e0289641. [PMID: 37535551 PMCID: PMC10399908 DOI: 10.1371/journal.pone.0289641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 07/21/2023] [Indexed: 08/05/2023] Open
Abstract
Ophidiomycosis is a prevalent and intermittently pervasive disease of snakes globally caused by the opportunistic fungal pathogen, Ophidiomyces ophidiicola. Host response has yet to be fully explored, including the role of temperature in disease progression and hematologic changes. This study enrolled twelve adult prairie rattlesnakes (Crotalus viridis) in an experimental challenge with O. ophidiicola at two temperatures, 26°C (n = 6) and 20°C (n = 6). Each temperature cohort included four inoculated and two control snakes. Assessments involving physical exams, lesion swabbing, and hematology were performed weekly. Differences were observed between inoculated and control snakes in survival, behavior, clinical signs, ultraviolet (UV) fluorescence, hematologic response, and histologic lesions. All inoculated snakes held at 20°C were euthanized prior to study end date due to severity of clinical signs while only one inoculated animal in the 26°C trial met this outcome. In both groups, qPCR positive detection preceded clinical signs with regards to days post inoculation (dpi). However, the earliest appearance of gross lesions occurred later in the 20°C snakes (20 dpi) than the 26°C snakes (13 dpi). Relative leukocytosis was observed in all inoculated snakes and driven by heterophilia in the 20°C snakes, and azurophilia in the 26°C group. Histologically, 20°C snakes had more severe lesions, a lack of appropriate inflammatory response, and unencumbered fungal proliferation and invasion. In contrast, 26°C snakes had marked granulomatous inflammation with encapsulation of fungi and less invasion and dissemination. The results of this study identified that O. ophidiicola-infected rattlesnakes exposed to lower temperatures have decreased survival and more robust hematologic change, though minimal and ineffective inflammatory response at site of infection. Ophidiomycosis is a complex disease with host, pathogen, and environmental factors influencing disease presentation, progression, and ultimately, survival. This study highlighted the importance of temperature as an element impacting the host response to O. ophidiicola.
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Affiliation(s)
- Michelle Waligora Kendall
- Wildlife Epidemiology Lab, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Allison D Wright
- Wildlife Epidemiology Lab, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Laura A Adamovicz
- Wildlife Epidemiology Lab, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
- The Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Kennymac Durante
- Wildlife Epidemiology Lab, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Kirsten E Andersson
- Wildlife Epidemiology Lab, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Kelcie Frederickson
- Wildlife Epidemiology Lab, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Katie Vivirito
- Wildlife Epidemiology Lab, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Emilie A Ospina
- Wildlife Epidemiology Lab, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
- The Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
| | - Martha A Delaney
- Zoological Pathology Program, University of Illinois, Brookfield, IL, United States of America
| | - Matthew C Allender
- Wildlife Epidemiology Lab, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
- The Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois, United States of America
- The Brookfield Zoo, Chicago Zoological Society, Brookfield, Illinois, United States of America
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Lima AS, de Figueredo AC, Floreste FR, Garcia Neto PG, Gomes FR, Titon SCM. Temperature Extreme Events Decrease Endocrine and Immune Reactive Scope in Bullfrogs (Lithobates catesbeianus). Integr Comp Biol 2022; 62:1671-1682. [PMID: 35771987 DOI: 10.1093/icb/icac105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 06/23/2022] [Accepted: 06/24/2022] [Indexed: 01/05/2023] Open
Abstract
Currently, effects of increased atmospheric temperature, in the context of ongoing climate change, have been investigated in multiple organisms and levels of biological organization. While there has been a focus on the impacts of increased mean temperature, an emergent and equally important point is the consequences of recurrent exposure to extreme temperature events, simulating heat waves. This study investigated the effects of serial exposure to high temperatures on immune and endocrine variables before and after exposure to an acute secondary stressor in bullfrogs (Lithobates catesbeianus). Adult males were divided into three groups and subjected to three thermal regimes: control (c; constant 22°C); experimental 1 (E1; kept at 22°C and exposed to 4 days of 30°C every 16 days); and experimental 2 (E2; kept at 22°C and exposed to 4 days of 30°C every 6 days). Blood samples were collected on the last day of key extreme heat events. Two weeks after the last extreme heat event, animals were subjected to restraint stress (1 h) and sampled again. Blood samples were used to determine neutrophil: lymphocyte ratio, plasma bacterial killing ability, as well as, corticosterone and plasma testosterone levels. Overall, we found exposure to extreme heat events did not affect immune and endocrine variables over time. Meanwhile, the previous exposure to extreme heat events modulated the responsiveness to restraint. The amplitude of increased corticosterone plasma levels and neutrophil: lymphocyte ratio in response to restraint decreased with the number of previous exposures to extreme heat events. These results suggest that exposure to extreme climatic events has hidden effects on bullfrog's stress response, expressed as diminished reactive scope to a novel stressor. This represents a highly deleterious facet of climate change since diminished responsiveness prevents proper coping with wildlife challenges.
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Affiliation(s)
- Alan Siqueira Lima
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brazil
| | - Aymam Cobo de Figueredo
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brazil
| | - Felipe Rangel Floreste
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brazil
| | - Patrício Getúlio Garcia Neto
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brazil
| | - Fernando Ribeiro Gomes
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brazil
| | - Stefanny Christie Monteiro Titon
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brazil
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