Dampened virulence and limited proliferation of Batrachochytrium salamandrivorans during subclinical infection of the troglobiont olm (Proteus anguinus)

Abstract

Emerging infections add to existing threats to the survival of amphibians worldwide. The olm (Proteus anguinus) is a vulnerable, troglobiont urodele species with a small European range and restricted to underground karstic systems. Population declines to emerging threats like the chytrid fungus Batrachochytrium salamandrivorans, are likely to go unnoticed due to inaccessibility of the species’ habitat. We here studied the interaction between olms and B. salamandrivorans. Experimental inoculation of olms resulted in low-level, asymptomatic but persistent infections, with limbs as predilection sites. The lack of exponential fungal growth in the olms’ epidermis correlated with limited fungal proliferation and dampened virulence gene expression after exposure to olm skin compounds. The olm is one of few western Palearctic urodeles that is tolerant to B. salamandrivorans infection and may act as a subterranean disease reservoir, yet costs of subclinical infection may compromise olm fitness on the long term.

Geographic risk assessment ofBatrachochytrium salamandrivoransinvasion in Costa Rica as a means of informing emergence management and mitigation

“…The pathogen has now been detected in wild amphibians in nine countries and, while it has not yet been detected in the Americas, it is known to infect at least 16 species native to the Americas (60). As our knowledge grows, so does the list of potential host species, with a recent detection in Rana temporaria in Germany (61) and a successful experimental inoculation in Proteus anguinus (62). We can proactively plan for Bsal in part by modeling the potential risk of invasion based on environmental suitability, amphibian biodiversity, and tourist visitation in protected areas.…”

From Cave Dragons to Genomics: Advancements in the Study of Subterranean Tetrapods

“…Threats to cave life include habitat destruction (Elliott 2012 , Furey and Racey 2015 , Gallão and Bichuette 2018 ), aquifer overexploitation (Griebler et al 2019 ), climate change (Mammola et al 2019 ), pollution (du Preez et al 2016 , Gallão and Bichuette 2018 ), tourism (Ferreira et al 2020 ), and transported diseases (Reynolds and Barton 2014 , Li et al 2020 ). A major threat to aquatic cave salamanders is the pollution and exploitation of groundwater aquifers and cave waters (Miller and Niemiller 2008 , Pezdirc et al 2011 , Bendik et al 2014 , Ribeiro and Tičar 2017 , Devitt et al 2019 ).…”

“…As cave salamanders occur in these regions and may therefore be exposed to chytrid fungus, this is a major concern. Thus far, no cave salamander populations have tested positive for the fungus (Fenolio et al 2013 , Kostanjšek et al 2019 ), and there are indications that Proteus salamanders show some tolerance to B. salamandrivorans (Li et al 2020 ). However, the overall impact that the disease may have on natural populations is currently impossible to assess, and minimizing the potential for contact should be prioritized.…”

Cultivable Skin Mycobiota of Healthy and Diseased Blind Cave Salamander (Proteus anguinus)

“…Due to the unique physiology and ecology of amphibians, water is one of the main vectors for transmission of these pathogens (Robert et al, 2011). Although it is known that stressed animals in captivity can become infected via traumatized gills or skin and through contact with contaminated 1 http://www.edgeofexistence.org/species/olm/ water (Seyedmousavi et al, 2013), only three reports on fungal infections of olms in captivity have been published so far (Kogej, 1999;Bizjak-Mali et al, 2018;Lukač et al, 2019;Li et al, 2020), and no data exist on fungal infections of the olm in its natural underground habitats.…”