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Brannelly LA, Sharma P, Ballesteros S, Wendt AS. Voriconazole successfully treats chytridiomycosis in frogs. DISEASES OF AQUATIC ORGANISMS 2024; 159:1-7. [PMID: 38989788 DOI: 10.3354/dao03795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
Chytridiomycosis is a devastating disease and is a key cause of amphibian population declines around the world. Despite active research on this amphibian disease system for over 2 decades, we still do not have treatment methods that are safe and that can be broadly used across species. Here, we show evidence that voriconazole is a successful method of treatment for 1 species of amphibian in captivity and that this treatment could offer benefits over other treatment options like heat or itraconazole, which are not able to be used for all species and life stages. We conducted 2 treatments of chytridiomycosis using voriconazole. The treatment was effective and resulted in 100% pathogen clearance, and mortality ceased. Additionally, treating frogs with voriconazole requires less handling than treatment methods like itraconazole and requires no specialized equipment, like heat treatment. We highlight that clinical treatment trials should be conducted to identify an optimum dosage and treatment time and that trials should test whether this treatment is safe and effective for tadpoles and other species.
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Affiliation(s)
- Laura A Brannelly
- Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Preeti Sharma
- Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Werribee, Victoria 3030, Australia
- Centre for Planetary Health and Food Security, School of Environment and Science, Griffith University, Southport, Queensland 4215, Australia
| | - Sofia Ballesteros
- Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Alexander S Wendt
- Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Werribee, Victoria 3030, Australia
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Llewelyn VK, Berger L, Glass BD. Predicting in vivo absorption of chloramphenicol in frogs using in vitro percutaneous absorption data. BMC Vet Res 2021; 17:57. [PMID: 33509166 PMCID: PMC7842057 DOI: 10.1186/s12917-021-02765-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 01/13/2021] [Indexed: 12/15/2022] Open
Abstract
Background Infectious disease, particularly the fungal disease chytridiomycosis (caused by Batrachochytrium dendrobatidis), is a primary cause of amphibian declines and extinctions worldwide. The transdermal route, although offering a simple option for drug administration in frogs, is complicated by the lack of knowledge regarding percutaneous absorption kinetics. This study builds on our previous studies in frogs, to formulate and predict the percutaneous absorption of a drug for the treatment of infectious disease in frogs. Chloramphenicol, a drug with reported efficacy in the treatment of infectious disease including Batrachochytrium dendrobatidis, was formulated with 20% v/v propylene glycol and applied to the ventral pelvis of Rhinella marina for up to 6 h. Serum samples were taken during and up to 18 h following exposure, quantified for chloramphenicol content, and pharmacokinetic parameters were estimated using non-compartmental analysis. Results Serum levels of chloramphenicol reached the minimum inhibitory concentration (MIC; 12.5 μg.mL− 1) for Batrachochytrium dendrobatidis within 90–120 min of exposure commencing, and remained above the MIC for the remaining exposure time. Cmax (17.09 ± 2.81 μg.mL− 1) was reached at 2 h, while elimination was long (t1/2 = 18.68 h). Conclusions The model, based on in vitro data and adjusted for formulation components and in vivo data, was effective in predicting chloramphenicol flux to ensure the MIC for Batrachochytrium dendrobatidis was reached, with serum levels being well above the MICs for other common bacterial pathogens in frogs. Chloramphenicol’s extended elimination means that a 6-h bath may be adequate to maintain serum levels for up to 24 h. We suggest trialling a reduction of the currently-recommended continuous (23 h/day for 21–35 days) chloramphenicol bathing for chytrid infection with this formulation. Supplementary Information The online version contains supplementary material available at 10.1186/s12917-021-02765-5.
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Affiliation(s)
- Victoria K Llewelyn
- Pharmacy, College of Medicine and Dentistry, James Cook University, Townsville, Australia. .,College of Nursing and Health Sciences, Flinders University, Adelaide, Australia.
| | - Lee Berger
- One Health Research Group, Melbourne Veterinary School, University of Melbourne, Werribee, Australia
| | - Beverley D Glass
- Pharmacy, College of Medicine and Dentistry, James Cook University, Townsville, Australia
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Burns TJ, Scheele BC, Brannelly LA, Clemann N, Gilbert D, Driscoll DA. Indirect terrestrial transmission of amphibian chytrid fungus from reservoir to susceptible host species leads to fatal chytridiomycosis. Anim Conserv 2020. [DOI: 10.1111/acv.12665] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Thomas J. Burns
- Centre for Integrative Ecology School of Life and Environmental Sciences Deakin University (Burwood Campus) Geelong Vic. Australia
| | - Ben C. Scheele
- Fenner School of Environment and Society Australian National University Canberra ACT Australia
| | - Laura A. Brannelly
- Melbourne Veterinary School Faculty of Veterinary and Agricultural Sciences University of Melbourne Werribee Vic. Australia
| | - Nick Clemann
- Department of Environment, Land, Water and Planning Arthur Rylah Institute for Environmental Research Heidelberg Vic. Australia
| | - Deon Gilbert
- Wildlife Conservation and Science. Zoos Victoria Parkville Vic. Australia
| | - Don A. Driscoll
- Centre for Integrative Ecology School of Life and Environmental Sciences Deakin University (Burwood Campus) Geelong Vic. Australia
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Brannelly LA, Martin G, Llewelyn J, Skerratt LF, Berger L. Age- and size-dependent resistance to chytridiomycosis in the invasive cane toad Rhinella marina. DISEASES OF AQUATIC ORGANISMS 2018; 131:107-120. [PMID: 30460917 DOI: 10.3354/dao03278] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In Australia, the cane toad Rhinella marina and chytrid fungus Batrachochytrium dendrobatidis (Bd) are examples of invasive species that have had dramatic impacts on native fauna. However, little is known about the interaction between Bd and cane toads. We aimed to explore the interaction of these 2 species in 3 parts. First, we collated data from the literature on Bd infection in wild cane toads. Second, we tested the susceptibility of recently metamorphosed cane toads to Bd infection. Finally, we modelled the distribution of the 2 species in Australia to identify where they overlap and, therefore, might interact. Through our data collation, we found that adult cane toads are infrequently infected and do not carry high infection burdens; however, our infection experiment showed that metamorphs are highly susceptible to infection and disease, but resistance appears to increase with increasing toad size. Niche modelling revealed overlapping distributions and the potential for cane toads to be affected by chytridiomycosis in the wild. While Bd can cause mortality in small juveniles in the laboratory, warm microhabitats used by wild toads likely prevent infection, and furthermore, high mortality of juveniles is unlikely to affect the adult populations because they are highly fecund. However, to demonstrate the impact of Bd on wild cane toad populations, targeted field studies are required to assess (1) the overall impact of chytridiomycosis on recruitment especially in cooler areas more favourable for Bd and (2) whether cane toad juveniles can amplify Bd exposure of native amphibian species in these areas.
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Affiliation(s)
- Laura A Brannelly
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA
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Kosch TA, Silva CNS, Brannelly LA, Roberts AA, Lau Q, Marantelli G, Berger L, Skerratt LF. Genetic potential for disease resistance in critically endangered amphibians decimated by chytridiomycosis. Anim Conserv 2018. [DOI: 10.1111/acv.12459] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- T. A. Kosch
- One Health Research Group College of Public Health, Medical and Veterinary Sciences James Cook University Townsville Qld Australia
| | - C. N. S. Silva
- Centre for Sustainable Tropical Fisheries and Aquaculture College of Science and Engineering James Cook University Townsville Qld Australia
| | - L. A. Brannelly
- One Health Research Group College of Public Health, Medical and Veterinary Sciences James Cook University Townsville Qld Australia
- Department of Biological Sciences University of Pittsburgh Pittsburgh PA USA
| | - A. A. Roberts
- One Health Research Group College of Public Health, Medical and Veterinary Sciences James Cook University Townsville Qld Australia
| | - Q. Lau
- Department of Evolutionary Studies of Biosystems Sokendai (The Graduate University for Advanced Studies) Hayama Japan
| | | | - L. Berger
- One Health Research Group College of Public Health, Medical and Veterinary Sciences James Cook University Townsville Qld Australia
| | - L. F. Skerratt
- One Health Research Group College of Public Health, Medical and Veterinary Sciences James Cook University Townsville Qld Australia
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Roberts AA, Berger L, Robertson SG, Webb RJ, Kosch TA, McFadden M, Skerratt LF, Glass BD, Motti CA, Brannelly LA. The efficacy and pharmacokinetics of terbinafine against the frog-killing fungus (Batrachochytrium dendrobatidis). Med Mycol 2018; 57:204-214. [DOI: 10.1093/mmy/myy010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Alexandra A Roberts
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Australia
| | - Lee Berger
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Australia
| | - Sherryl G Robertson
- Pharmacy, College of Medicine and Dentistry, James Cook University, Townsville, Australia
| | - Rebecca J Webb
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia
| | - Tiffany A Kosch
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Australia
| | - Michael McFadden
- Taronga Conservation Society Australia, Herpetofauna Division, Mosman, Australia
| | - Lee F Skerratt
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Australia
| | - Beverley D Glass
- Pharmacy, College of Medicine and Dentistry, James Cook University, Townsville, Australia
| | - Cherie A Motti
- Australian Institute of Marine Science, Townsville, Australia
| | - Laura A Brannelly
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia
- Department of Biological Sciences, University of Pittsburgh, Pittsburg, Pennsylvania, USA
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Brannelly LA, Webb R, Skerratt LF, Berger L. Amphibians with infectious disease increase their reproductive effort: evidence for the terminal investment hypothesis. Open Biol 2017; 6:rsob.150251. [PMID: 27358291 PMCID: PMC4929933 DOI: 10.1098/rsob.150251] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 06/01/2016] [Indexed: 12/13/2022] Open
Abstract
Mounting an immune response to fight disease is costly for an organism and can reduce investment in another life-history trait, such as reproduction. The terminal investment hypothesis predicts that an organism will increase reproductive effort when threatened by disease. The reproductive fitness of amphibians infected with the deadly fungal pathogen Batrachochytrium dendrobatidis (Bd) is largely unknown. In this study, we explored gametogenesis in two endangered and susceptible frog species, Pseudophryne corroboree and Litoria verreauxii alpina. Gametogenesis, both oogenesis and spermatogenesis, increased when animals were experimentally infected with Bd. In P. corroboree, infected males have thicker germinal epithelium, and a larger proportion of spermatocytes. In L. v. alpina, infected males had more spermatic cell bundles in total, and a larger proportion of spermatozoa bundles. In female L. v. alpina, ovaries and oviducts were larger in infected animals, and there were more cells present within the ovaries. Terminal investment has consequences for the evolution of disease resistance in declining species. If infected animals are increasing reproductive efforts and producing more offspring before succumbing to disease, it is possible that population-level selection for disease resistance will be minimized.
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Affiliation(s)
- Laura A Brannelly
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia
| | - Rebecca Webb
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia
| | - Lee F Skerratt
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Lee Berger
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
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THE PHARMACOKINETICS OF TOPICAL ITRACONAZOLE IN PANAMANIAN GOLDEN FROGS (ATELOPUS ZETEKI). J Zoo Wildl Med 2017; 48:344-351. [DOI: 10.1638/2015-0218r2.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Brannelly LA, Roberts AA, Skerratt LF, Berger L. Epidermal cell death in frogs with chytridiomycosis. PeerJ 2017; 5:e2925. [PMID: 28168107 PMCID: PMC5291105 DOI: 10.7717/peerj.2925] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 12/19/2016] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Amphibians are declining at an alarming rate, and one of the major causes of decline is the infectious disease chytridiomycosis. Parasitic fungal sporangia occur within epidermal cells causing epidermal disruption, but these changes have not been well characterised. Apoptosis (planned cell death) can be a damaging response to the host but may alternatively be a mechanism of pathogen removal for some intracellular infections. METHODS In this study we experimentally infected two endangered amphibian species Pseudophryne corroboree and Litoria verreauxii alpina with the causal agent of chytridiomycosis. We quantified cell death in the epidermis through two assays: terminal transferase-mediated dUTP nick end-labelling (TUNEL) and caspase 3/7. RESULTS Cell death was positively associated with infection load and morbidity of clinically infected animals. In infected amphibians, TUNEL positive cells were concentrated in epidermal layers, correlating to the localisation of infection within the skin. Caspase activity was stable and low in early infection, where pathogen loads were light but increasing. In animals that recovered from infection, caspase activity gradually returned to normal as the infection cleared. Whereas, in amphibians that did not recover, caspase activity increased dramatically when infection loads peaked. DISCUSSION Increased cell death may be a pathology of the fungal parasite, likely contributing to loss of skin homeostatic functions, but it is also possible that apoptosis suppression may be used initially by the pathogen to help establish infection. Further research should explore the specific mechanisms of cell death and more specifically apoptosis regulation during fungal infection.
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Affiliation(s)
- Laura A Brannelly
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University , Townsville , QLD , Australia
| | - Alexandra A Roberts
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University , Townsville , QLD , Australia
| | - Lee F Skerratt
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia; Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Lee Berger
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia; Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Victoria, Australia
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Brannelly LA, Webb RJ, Skerratt LF, Berger L. Effects of chytridiomycosis on hematopoietic tissue in the spleen, kidney and bone marrow in three diverse amphibian species. Pathog Dis 2016; 74:ftw069. [DOI: 10.1093/femspd/ftw069] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2016] [Indexed: 01/12/2023] Open
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