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

The fungal pathogen <italic>Batrachochytrium dendrobatidis</italic> (<italic>Bd</italic>), 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 (<italic>Rana dalmatina</italic>), against two isolates (IA042 and Hung_2014) of the highly virulent Global Pandemic Lineage (GPL) of <italic>Bd</italic>. Our results showed for the first time that Brevinin-1Da can inhibit the growth of <italic>Bd</italic>, 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 <italic>Bd</italic> isolate Hung_2014, which was isolated in the core area of <italic>Rana dalmatina</italic>’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 <italic>Bd</italic> to the chemical defence of hosts can vary depending on the isolate. [ABSTRACT FROM AUTHOR]