Amphibian Pathogen Batrachochytrium dendrobatidis Is Inhibited by the Cutaneous Bacteria of Amphibian Species

Harris, Reid N.; James, Timothy Y.; Lauer, Antje; Simon, Mary Alice; Patel, Amit

doi:10.1007/s10393-005-0009-1

Cited by 264 publications

(319 citation statements)

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“…Research is underway (by P.A.B.) to study potential ecoimmunologic mechanisms of coquis, including symbiotic antiBd bacteria on the skin (Harris et al 2006), which could provide insight into how adult coquis clear infection. It is unknown when the immune system of direct-developing frogs matures.…”

Section: Discussionmentioning

confidence: 99%

SUSCEPTIBILITY TO THE AMPHIBIAN CHYTRID FUNGUS VARIES WITH ONTOGENY IN THE DIRECT-DEVELOPING FROG,ELEUTHERODACTYLUS COQUI

Langhammer

Burrowes

Lips

et al. 2014

Journal of Wildlife Diseases

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ABSTRACT:Age-related differences in susceptibility to infectious disease are known from a wide variety of plant and animal taxonomic groups. For example, the immature immune systems of young vertebrates, along with limited prior exposure to pathogens and behavioral factors, can place juveniles at greater risk of acquiring and succumbing to a pathogen. We studied the ontogenetic susceptibility of terrestrial direct-developing frogs (Eleutherodactylus coqui) to the fungal pathogen, Batrachochytrium dendrobatidis (Bd), which is responsible for the decline of amphibian species worldwide. By exposing juvenile and adult frogs to the same dose and strain of Bd, we uncovered ontogenetic differences in susceptibility. Froglets exposed to the pathogen had significantly lower survival rates compared with control froglets, while adult frogs largely cleared infection and had survival rates indistinguishable from control frogs, even when exposed to a much higher dose of Bd. The high disease-induced mortality rate of juveniles may explain ongoing population declines in eastern Puerto Rico, where Bd is endemic and juveniles experience higher prevalence and infection intensity compared to adults. Our results have important implications for understanding and modeling the decline, possibly to extinction, of amphibian populations and species.

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Section: Discussionmentioning

confidence: 99%

SUSCEPTIBILITY TO THE AMPHIBIAN CHYTRID FUNGUS VARIES WITH ONTOGENY IN THE DIRECT-DEVELOPING FROG,ELEUTHERODACTYLUS COQUI

Langhammer

Burrowes

Lips

et al. 2014

Journal of Wildlife Diseases

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“…A decade ago, Harris and co-workers discovered that a subset of bacteria isolated from the skin of living amphibians has the ability to inhibit Bd growth in vitro [33]. Since then bacteria that inhibit Bd have been isolated from amphibians from across the Americas, Africa, Europe and Australia.…”

Section: Trialled and Testedmentioning

confidence: 99%

Mitigating amphibian chytridiomycoses in nature

Garner

Schmidt²,

Martel

et al. 2016

Phil. Trans. R. Soc. B

128

151

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Amphibians across the planet face the threat of population decline and extirpation caused by the disease chytridiomycosis. Despite consensus that the fungal pathogens responsible for the disease are conservation issues, strategies to mitigate their impacts in the natural world are, at best, nascent. Reducing risk associated with the movement of amphibians, non-amphibian vectors and other sources of infection remains the first line of defence and a primary objective when mitigating the threat of disease in wildlife. Amphibian-associated chytridiomycete fungi and chytridiomycosis are already widespread, though, and we therefore focus on discussing options for mitigating the threats once disease emergence has occurred in wild amphibian populations. All strategies have shortcomings that need to be overcome before implementation, including stronger efforts towards understanding and addressing ethical and legal considerations. Even if these issues can be dealt with, all currently available approaches, or those under discussion, are unlikely to yield the desired conservation outcome of disease mitigation. The decision process for establishing mitigation strategies requires integrated thinking that assesses disease mitigation options critically and embeds them within more comprehensive strategies for the conservation of amphibian populations, communities and ecosystems. This article is part of the themed issue ‘Tackling emerging fungal threats to animal health, food security and ecosystem resilience’.

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“…Lips 1999, Daszak et al 2004. Reasons for this variation are unresolved, although differences in skin microbiota (Harris et al 2006), innate and adaptive immune mechanisms (Rollins-Smith & Conlon 2005, Ramsey et al 2010, Savage & Zamudio 2011, environmental factors (Gahl et al 2011), and behavior (Rowley & Alford 2007, Richards-Zawacki 2010 may play a role.…”

Section: Introductionmentioning

confidence: 99%

Host invasion by Batrachochytrium dendrobatidis: fungal and epidermal ultrastructure in model anurans

Greenspan¹,

Longcore²,

Calhoun³

2012

Dis. Aquat. Org.

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The chytridiomycete fungus Batrachochytrium dendrobatidis (Bd) colonizes mouthparts of amphibian larvae and superficial epidermis of post-metamorphic amphibians, causing the disease chytridiomycosis. Fungal growth within host cells has been documented by light and transmission electron microscopy; however, entry of the fungus into host cells has not. Our objective was to document how Bd enters host cells in the wood frog Lithobates sylvaticus, a species at high mortality risk for chytridiomycosis, and the bullfrog L. catesbeianus, a species at low mortality risk for chytridiomycosis. We inoculated frogs and documented infection with transmission electron microscopy. Zoospores encysted on the skin surface and produced morphologically similar germination tubes in both host species that penetrated host cell membranes and enabled transfer of zoospore contents into host cells. Documenting fungal and epidermal ultrastructure during host invasion furthers our understanding of Bd development and the pathogenesis of chytridiomycosis. KEY WORDS: Chytridiomycosis · Morphology · Transmission electron microscopy · Lithobates catesbeianus · Lithobates sylvaticus Resale or republication not permitted without written consent of the publisherDis Aquat Org 100: [201][202][203][204][205][206][207][208][209][210] 2012 scopically, excessive skin sloughing, lethargy, anorexia, loss of righting reflex, and abnormal posture may be observed (Nichols et al. 2001, Daszak et al. 2004) but often not until immediately before death (Bradley et al. 2002, Parker et al. 2002. Proximate cause of death is inhibition of electrolyte transport across epidermis and subsequent disruption of cardiac electrical activity (Voyles et al. 2009).The asexual life cycle of Bd consists of a motile zoospore stage and a stationary thallus stage (Berger et al. 2005). Zoospores are flagellated and are not bounded by a cell wall. After a motile period, usually lasting ≤24 h, a zoospore encysts (i.e. attaches to a substrate, retracts the flagellum, and forms a wall of chitin around the spore body). Morphology after encystment depends on substrate type. On nutrient media, an encysted zoospore develops into a single or colonial (internally divided) zoosporangium (endogenous growth); root-like rhizoids originating from 1 or more points on the zoosporangium may be numerous . In an amphibian host, cellular contents of a superficially encysted zoospore leave the cyst and enter a host cell (exogenous growth), inside which a single or colonial zoosporangium develops; rhizoids are usually less abundant than on nutrient media (Berger et al. 2005). The specifics of amphibian host invasion by Bd (i.e. the morphological process by which zoospore contents are transferred from a cyst into a host cell) have not been reported. In other chytrid species with known developmental morphologies (saprophytes and patho gens of plants, algae, protists, and invertebrates), endobiotic (i.e. intracellular) growth of a thallus is initiated when a protrusion of the zoospore cyst wall e...

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Amphibian Pathogen Batrachochytrium dendrobatidis Is Inhibited by the Cutaneous Bacteria of Amphibian Species

Cited by 264 publications

References 10 publications

SUSCEPTIBILITY TO THE AMPHIBIAN CHYTRID FUNGUS VARIES WITH ONTOGENY IN THE DIRECT-DEVELOPING FROG,ELEUTHERODACTYLUS COQUI

SUSCEPTIBILITY TO THE AMPHIBIAN CHYTRID FUNGUS VARIES WITH ONTOGENY IN THE DIRECT-DEVELOPING FROG,ELEUTHERODACTYLUS COQUI

Mitigating amphibian chytridiomycoses in nature

Host invasion by Batrachochytrium dendrobatidis: fungal and epidermal ultrastructure in model anurans

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