Epidermal cell death in frogs with chytridiomycosis

Brannelly, Laura A., Roberts, Alexandra A., Skerratt, Lee F., and Berger, Lee (2017) Epidermal cell death in frogs with chytridiomycosis. PeerJ, 5. e2925. pp. 1-20.

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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.

Item ID: 46997
Item Type: Article (Research - C1)
ISSN: 2167-8359
Keywords: apoptosis, caspases, chytridiomycosis, TUNEL, wildlife disease
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© Copyright 2017 Brannelly et al. Distributed under Creative Commons CC-BY 4.

Funders: Australian Research Council (ARC), Queensland Government Accelerate Fellowship, Queensland Department of Environment and Heritage, Taronga Conservation Science Initiative
Projects and Grants: ARC FT100100375, ARC LP110200240 , ARC DP120100811
Date Deposited: 01 Feb 2017 23:29
FoR Codes: 30 AGRICULTURAL, VETERINARY AND FOOD SCIENCES > 3009 Veterinary sciences > 300910 Veterinary pathology @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960899 Flora, Fauna and Biodiversity of Environments not elsewhere classified @ 100%
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