In vitro efficacy of the skin peptide Brevinin-1Da against two isolates of the Global Pandemic Lineage of the amphibian chytrid fungus, Batrachochytrium dendrobatidis

The fungal pathogen Batrachochytrium dendrobatidis (Bd), causing chytridiomycosis, continues to threaten the existence of hundreds of amphibian species worldwide. It has remained difficult to predict the sensitivity of species to the disease, but skin-secreted antimicrobial peptides have been proposed to provide effective defences. In this study we tested this hypothesis by assessing in vitro the bioactivity of the antimicrobial peptide Brevinin-1Da, which is known to be synthesized in the skin of agile frogs (Rana dalmatina), against two isolates (IA042 and Hung_2014) of the highly virulent Global Pandemic Lineage (GPL) of Bd. Our results showed for the first time that Brevinin-1Da can inhibit the growth of Bd, and its efficacy appeared to be similar to that of other members of the Brevinin-1 peptide family isolated from other Ranid frogs. Finally, efficacy of Brevinin-1Da appeared to be higher against the Bd isolate Hung_2014, which was isolated in the core area of Rana dalmatina’s geographic distribution, and lower against IA042, which was isolated from outside the current distribution of this frog species. These results show that the efficacy of Brevinin-1Da may contribute to the previously documented resistance of agile frogs and that the sensitivity of Bd to the chemical defence of hosts can vary depending on the isolate.