Successful Drug-Mediated Host Clearance of Batrachochytrium salamandrivorans

Abstract

Skin fungi are among the most dangerous drivers of global amphibian declines, and few mitigation strategies are known. For Batrachochytrium salamandrivorans (Chytridiomycota), available treatments rely on temperature, partially combined with antifungal drugs. We report the clearance of B. salamandrivorans in 2 urodelan species using a solely drug-based approach.

Using FINDeM for rapid, CRISPR-based detection of the emerging salamandrid fungal pathogen,Batrachochytrium salamandrivorans

“…We also evaluated the efficacy of qPCR and FINDeM in duplicate on paired swab samples from 22 newts of three different species ( Triturus cristatus , Lissotriton helveticus , Ichthyosaura alpestris , Supplemental Table 1). Two skin swabs per individual were collected at three different sites during local monitoring projects between 2020 and 2023 with one set of swabs undergoing kit-based DNA extraction soon after collection (hereafter, “Kit”; Qiagen Blood & Tissue following (27) or PrepMan Ultra following the manufacturer’s instructions) and the other set of swabs being stored at −20C° until “quick” DNA extraction (hereafter, “Quick”; Fig. 1; 21) in Fall 2023.…”

“…We also evaluated the efficacy of qPCR and FINDeM in duplicate on paired swab samples from 22 newts of three different species (Triturus cristatus, Lissotriton helveticus, Ichthyosaura alpestris, Supplemental Table 1). Two skin swabs per individual were collected at three different sites during local monitoring projects between 2020 and 2023 with one set of swabs undergoing kit-based DNA extraction soon after collection (hereafter, "Kit"; Qiagen Blood & Tissue following (27) or PrepMan Ultra following the manufacturer's instructions) and the other set of swabs being stored at -20C° until "quick" DNA extraction (hereafter, "Quick"; FINDeM's LOD, to assess a quick extraction technique that allows on-site diagnostics, and to account for variation between host species and possibly distinct Bsal lineages (28). Additionally, we used sterile swabs and DNA extracts of cultured zoospores as negative and positive controls, respectively.…”

“…This is especially important for some newt and anuran species that can carry Bsal without expressing clinical signs of infection; essentially serving as Bsal reservoirs that can act as 'silent spreaders' of the pathogen to more sensitive species (33). FINDeM now allows researchers to identify infected specimens directly in the field with molecular sensitivity, which might be needed for several containment strategies such as drug-based in situ treatments (27) or even removal of infected hosts (16). Further, in situ detection may also help to selectively collect Bsal isolates only from confirmed-infected hosts, thus limiting the effort spent trying to isolate Bsal from uninfected individuals while enabling a deeper understanding of the dispersal and evolution of localized Bsal isolates which have been shown to vary greatly in their ecological niche (28).…”