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Amphibians have been experiencing unprecedented population declines and extinctions around the globe. While there are multiple causes, emerging infectious disease is a main driver. The newly identified Salamander-eating fungus, Batrachochytrium salamandrivorans (Bsal) poses an immense threat to global salamander diversity. From red-spotted newts to one of the largest and most ancient species, the hellbenders, North America is a hotspot of salamander diversity rivaled by no other around the world. Consequently, understanding and managing disease threats like that posed by Bsal, are of the utmost importance for conservation.

 

Currently, we have the rare opportunity to be proactive in assessing disease risk and developing effective conservation strategies to reduce Bsal-associated declines before this fungus wreaks havoc on North American salamanders. Currently I'm working to (1) develop a “landscape of risk” focused on wild populations of the Bsal susceptible species, the eastern newt, and other co-occurring salamanders across the Eastern US by assessing and characterizing correlates of disease risk, including host mucosome function and environmental factors, and (2) test the efficacy of multiple disease mitigation tactics, including vaccination, probiotic bioaugmentation of the skin, and environmental micropredator augmentation.

 

Landscape of Risk: Host and environmental factors shape pathogen dynamics and disease outcome. The pathogen responsible for salamander chytridiomycosis, Batrachochytrium salamandrivorans, puts North America’s salamander diversity at risk. Through proactive research we have the potential to test hypotheses of immunological ecology and to prepare for the conservation challenge at hand. My David H. Smith Conservation Postdoctoral Fellowship research, characterizes host susceptibility and environmental suitability of Bsal. From the environmental perspective, I am identifying Bsal’s tolerances to abiotic parameters including temperature, pH, and conductivity, and am exploring the ability of natural aquatic zooplankton to consume Bsal zoospores. From the host perspective, we am evaluating the function of skin mucosal defenses as a whole (host produced and microbial components) through a non-invasive mucosal wash. Host genetics and more specifically immune genes can also be key factors in disease susceptibility. I am characterizing Major Histocompatibility Complex (MHC) class II diversity to understand its role in host microbiome structure and disease susceptibility. Combining these different host and environmental determinants of disease risk, we can build a robust landscape of risk. In our world of increasing disease emergence, understanding which factors may play a role in the potential of amphibian species to persist through human-mediated disease emergence can strengthen our ecological understanding of disease and enable informed management decisions.

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Mitigation Strategies: We am working to identify Bsal-inhibiting bacteria from local amphibians, including eastern newts and two-lined salamanders, and to test probiotics as a disease response strategy. Such a strategy may be advantageous because antifungal bacteria can persist on the skin of some amphibians, and can be transferred through host-to-host or habitat-to-host contact thereby increasing “herd” (i.e., population) immunity. In addition to skin probiotics, novel vaccine strategies based on nanoparticle technology, and environmental micropredator addition, are promising potential tools I am exploring. In collaboration Dr. Kim Hamad Schifferli (Engineering,UMass-Boston), I am working to develop nanotoxoid vaccines, testing the hypothesis that these coated particles can present proteins to the host’s immune system and boost host immunity to allow amphibian survival. Testing these strategies individually and in combination to pinpoint effective and integrative disease mitigation strategies that can facilitate population persistence through disease emergence