Metabolites from the fungal pathogen Batrachochytrium dendrobatidis (Bd) reduce Bd load in Cuban treefrog tadpoles.
Abstract
Batrachochytrium dendrobatidis (Bd) has been associated with massive amphibian population declines worldwide. Wildlife vaccination campaigns have proven effective for mitigating damage from other pathogens, and there is evidence that adult frogs can acquire resistance to Bd when exposed to killed Bd zoospores and the metabolites they produced. Here, we investigated whether Cuban treefrogs tadpoles Osteopilus septentrionalis can gain protection from Bd through exposure to a prophylaxis treatment composed of killed zoospores or soluble Bd metabolites. We used a 2 × 2 factorial design, crossing the presence or absence of killed zoospores with the presence or absence of Bd metabolites. All hosts were subsequently exposed to live Bd to evaluate susceptibility. Exposure to killed zoospores did not induce a protective response. However, tadpoles exposed to Bd metabolites had significantly lower Bd intensity and prevalence than tadpoles that were not exposed to metabolites. The metabolites Bd produce pose no risk of Bd infection and therefore make an epidemiologically safe prophylaxis treatment, protecting tadpoles against Bd. This work provides a promising potential for protecting amphibians in the wild as a disease management strategy for controlling Bd-associated declines.