Barrier defenses in amphibian skin against chytridiomycosis: Additional lessons from microbial reduction experiments

Background/Question/Methods:  A great concern of biologists is the continuing loss of global biodiversity.  Amphibian species have experienced unprecedented declines due to a global pandemic disease, chytridiomycosis, caused by the chytrid fungus Batrachochytrium dendrobatidis.  This presentation will attempt to summarize our current understanding of immune defenses against chytridiomycosis, which include the skin microbiome. We will provide some new insights into disease outcome when the microbial community is reduced.

Results/Conclusions:  Using the southern leopard frog, Rana (Lithobates) sphenocephala, we showed that the skin of these animals harbors multiple bacteria species capable of inhibiting B. dendrobatidis growth in vitro, and that reduction of bacteria on post-metamorphic juvenile skin results in increased B. dendrobatidis infection.  Further, we present evidence that this innate bacteria-mediated skin defense precedes the development of an antimicrobial peptide skin defense in juveniles of this species, and thus provides some protection at a critical period of development.