Understanding longevity of immunisation approaches against the deadly amphibian chytrid fungus

The amphibian-killing chytrid fungus Batrachochytrium dendrobatidis (Bd) has devastated amphibian populations worldwide. Because Bd persists in ecosystems, conservation actions like translocations often fail. A promising research avenue for overcoming this exploits environmental tolerance mismatches between Bd and its hosts. Many amphibians tolerate or prefer temperatures detrimental to Bd, making clearing infections through warming a safe and effective treatment. In some frog species, infection followed by clearance increases resistance to future infections, providing immunity. While promising, most immunity studies have examined short-term responses, and the duration of immunity—critical for longer-lived species—remains unknown.

My PhD will determine if immunising Bd-susceptible frogs can provide long-term resistance to disease and improve conservation outcomes, focusing on two key objectives: 1) comparing reintroductions of immunised and non-immunised green and golden bell frogs (Litoria aurea) in the field, and 2) determining if immunisation is effective for long-lived northern corroboree frogs (NCF; Pseudophryne pengilleyi) and measuring the duration of immunity.

In my first year, I will experimentally determine NCF preferred body temperature (Tpref) using thermal gradients. I will then test if immunity can be induced via heat clearance at Tpref, by rechallenging previously infected—and cleared—NCFs with Bd. To evaluate immunity longevity, I will retest individuals in subsequent years. This project will directly inform conservation, providing a method that could improve translocation outcomes and deepen our understanding of host-pathogen interactions.