Antimicrobial Peptide Defenses in the Salamander, Ambystoma Tigrinum, Against Emerging Amphibian Pathogens

Sheafor, Brandon; Davidson, Elizabeth W.; Parr, Luke; Rollins‐Smith, Louise A.

doi:10.7589/0090-3558-44.2.226

Cited by 44 publications

(31 citation statements)

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“…For a second assay we diluted the most active extracts in sterile distilled water to 5% and 2.5% final concentrations in the zoospore/TGhL mixture. Bd densities at Day 0 and Day 2 were recorded using a Titertek Multiscan Plate Reader at 492 nm, and wells were also observed using an inverted microscope (Sheafor et al 2008). Because plant extracts alone led to darkening of TGhL, which was detected by the Titertek monitor, readings for extracts with TGhL without zoospores present were subtracted from readings for extracts with zoospores.…”

Section: In Vitro Experimentsmentioning

confidence: 99%

Potential influence of plant chemicals on infectivity of Batrachochytrium dendrobatidis

Davidson¹,

Larsen²,

Palmer³

2012

Dis. Aquat. Org.

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We explored whether extracts of trees frequently found associated with amphibian habitats in Australia and Arizona, USA, may be inhibitory to the fungal pathogen Batrachochytrium dendrobatidis (Bd), which has been associated with global amphibian declines. We used salamanders Ambystoma tigrinum as the model system. Salamanders acquired significantly lower loads of Bd when exposed on leaves and extracts from the river red gum Eucalyptus camaldulensis, and loads were also low in some animals exposed on extracts of 2 oak species, Quercus emoryi and Q. turbinella. Some previously infected salamanders had their pathogen loads reduced, and some were fully cured, by placing them in leaf extracts, although some animals also self cured when housed in water alone. A significant number of animals cured of Bd infections 6 mo earlier were found to be resistant to reinfection. These results suggest that plants associated with amphibian habitats should be taken into consideration when explaining the prevalence of Bd in these habitats and that some amphibians may acquire resistance to the fungus if previously cured.

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Section: In Vitro Experimentsmentioning

confidence: 99%

Potential influence of plant chemicals on infectivity of Batrachochytrium dendrobatidis

Davidson¹,

Larsen²,

Palmer³

2012

Dis. Aquat. Org.

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“…Secretion of cationic antimicrobial peptides may decrease the pH of the skin to create a hostile micro-environment. Lower pH on the dorsal surface, particularly during peptide discharge, may be a factor limiting infection there (Weldon & Du Preez 2006, North & Alford 2008, Sheafor et al 2008. Here, higher pH on the ventral surface with higher Bd loads may be a cause or consequence of infection.…”

Section: Mandipropamidmentioning

confidence: 99%

Treatment of amphibians infected with chytrid fungus: learning from failed trials with itraconazole, antimicrobial peptides, bacteria, and heat therapy

Woodhams

Geiger²,

Reinert³

et al. 2012

Dis. Aquat. Org.

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Amphibian conservation goals depend on effective disease-treatment protocols. Desirable protocols are species, life stage, and context specific, but currently few treatment options exist for amphibians infected with the chytrid fungus Batrachochytrium dendrobatidis (Bd). Treatment options, at present, include antifungal drugs and heat therapy, but risks of toxicity and sideeffects make these options untenable in some cases. Here, we report on the comparison of several novel treatments with a more generally accepted antifungal treatment in experimental scientific trials to treat Bd-infected frogs including Alytes obstetricans tadpoles and metamorphs, Bufo bufo and Limnodynastes peronii metamorphs, and Lithobates pipiens and Rana muscosa adults. The experimental treatments included commercial antifungal products (itraconazole, mandipropamid, steriplantN, and PIP Pond Plus), antimicrobial skin peptides from the Bd-resistant Pelophylax esculentus, microbial treatments (Pedobacter cryoconitis), and heat therapy (35°C for 24 h). None of the new experimental treatments were considered successful in terms of improving survival; however, these results may advance future research by indicating the limits and potential of the various protocols. Caution in the use of itraconazole is warranted because of observed toxicity in metamorphic and adult frogs, even at low concentrations. Results suggest that rather than focusing on a single cure-all, diverse lines of research may provide multiple options for treating Bd infection in amphibians. Learning from 'failed treatments' is essential for the timely achievement of conservation goals and one of the primary aims for a publicly accessible treatment database under development.

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“…Viral mRNA is detectable in the intestines of larval and adult African clawed frogs ( Xenopus laevis ) as early as 3 h after exposure to virus in water and then spreads to other tissues, suggesting that the intestines are a primary point of entry of waterborne virus in amphibians (Robert et al 2011 ). The skin may not be a common site of infection in metamorphosed amphibians because they secrete antimicrobial peptides on their skin, which can inactivate several types of pathogens, including FV3 and ATV (Chinchar et al , 2004Sheafor et al 2008 ; Rollins-Smith 2009 ). Brunner et al ( 2007 ), however, demonstrated that a 1 s skinto-skin contact out of water was suffi cient for transmission of ATV from infected, symptomatic tiger salamander larvae to uninfected larvae, so entry through the epithelium is possible at least during the larval stage.…”

Section: Ranavirus Transmission Within a Speciesmentioning

confidence: 99%

Ranavirus Ecology and Evolution: From Epidemiology to Extinction

et al. 2015

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Antimicrobial Peptide Defenses in the Salamander, Ambystoma Tigrinum, Against Emerging Amphibian Pathogens

Cited by 44 publications

References 50 publications

Potential influence of plant chemicals on infectivity of Batrachochytrium dendrobatidis

Potential influence of plant chemicals on infectivity of Batrachochytrium dendrobatidis

Treatment of amphibians infected with chytrid fungus: learning from failed trials with itraconazole, antimicrobial peptides, bacteria, and heat therapy

Ranavirus Ecology and Evolution: From Epidemiology to Extinction

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