Projects Completed This Year

Further development and testing of vaccine candidates against white nose syndrome in bats

Investigator: Jorge E. Osorio, School of Veterinary Medicine, University of Wisconsin-Madison

Funding: U.S. Geological Survey (National Wildlife Health Center)

Completed Date: August 31, 2021

Since its discovery in the US in 2006, white-nose syndrome (WNS), caused by the fungus Pseudogymnoascus destructans (Pd), has killed an estimated 7 million bats, causing significant population declines in numerous bat species, including the little brown bat.  Several recent studies conducted by our research team have provided proof-of-concept for oral delivery of vaccine antigens to bats and several vaccine candidates that could be used to protect bats from WNS.  Our research team has identified and targeted two potentially protective Pd antigens.  One is calnexin, a fungal antigen that is highly conserved among Ascomycete fungi, including Pd.  It resides on the endoplasmic reticulum of fungal cells and is displayed on the fungal surface.  Another potential vaccine candidate is a 27.9 kDa subtilisin-like serine protease, the most heavily secreted protein by Pd, which may be involved in fungal invasion of wing tissue. We propose to further develop and evaluate these potential vaccine candidates and methods for delivering oral vaccines to bats in both field and laboratory settings.  

Identifying Important Forage fish for Marbled Murrelets in Washington with High-throughput Sequencing

Investigator: M. Zachariah Peery, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison

Funding: U.S. Fish and Wildlife Service

Completed Date: August 30, 2021

Marbled murrelets are listed as “threatened” under the US Endangered Species Act due to the loss and fragmentation of their old-forest nesting habitat, and nest predation from syanthropic species. Understanding how changes in the marine environment threaten marbled murrelets and their foraging resources is challenged by a lack of basic dietary information.  Dietary information for murrelets is scarce because of the species’ secretive inland nesting habits, which make monitoring prey delivered to nests nearly impossible. New next-generation-sequencing (NGS) technologies provide a promising tool for characterizing marbled murrelet diet at the species level. NGS methods allow for the sequencing of massive amounts of prey DNA fragments collected from predator fecal material without very time consuming and expensive cellular cloning procedures. Forage fish and marine invertebrate trawls currently being conducted by the Washington Department of Fish and Wildlife, and marbled murrelet surveys conducted by Oregon State University, and Humboldt University provide a unique opportunity to assess prey selection by comparing prey use to indices of availability. We used NGS methods – coupled with ongoing forage species surveys – to characterize the diet of marbled murrelets in Washington, Oregon, and California. Murrelets consumed a high diversity of prey with 17 fish species and 10 invertebrates detected, indicating this species is a generalist forager – as has been suggested previously. However, in contrast to previous studies based on more traditional approaches, our results support Pacific herring (Clupea pallassi) as the primary food source for murrelets in Washington and Oregon (frequency of occurrence= 0.84 and 0.69, respectively), whereas Californian anchovy (Engraulis mordax) was the most commonly consumed prey in California (frequency of occurrence= 0.77). Diet composition varied among in Oregon where sample size allowed interannual comparison, with a decline in the proportional consumption of energy dense prey from 2017 to 2018 – potentially resulting from shifts in ocean conditions associated with marine climate warming events. Diet varied nearly significantly between males and females, largely because of differences in rare prey – with common and energy dense prey consumed in equal proportions perhaps because of similar inland flight behavior and thus energy demands between the sexes. Diet, however, did not vary according to breeding status as measured by the presence of a well-developed brood patch. In conclusion, our study offers the first detailed report on the diet of adult marbled murrelets, a threatened and coastal indicator species.

Prions in Plants: Defining the Risks

Investigator: Joel A. Pedersen, Departments of Soil Science and Civil & Environmental Engineering, University of Wisconsin-Madison

Funding: US Geological Survey (National Wildlife Health Center)

Completed Date: September 30, 2021

Transmissible spongiform encephalopathies (TSEs; prion diseases) are a family of invariably fatal neurodegenerative diseases that afflict a variety of mammalian species after a long incubation period (months to years). Animal TSEs have been a major concern to food safety since recognition in the 1990s that BSE can transmit to humans, presumably through consumption of BSE-infected meat. Of present concern to public health and food safety is CWD, the only TSE known to affect free-ranging species (wildlife). Along with an expanding geographical distribution, CWD prevalence in current epizootics is increasing and has been reported at >80% in some captive herds, including one in WI, and >50% in a free-ranging herd in WY. In environments likely to be contaminated with CWD, vegetation is ubiquitous. Plants absorb a variety of substances from soil, ranging from nutrients to contaminants. Plants may serve as a conduit between CWD-contaminated soils and naïve deer hosts. This project established the ability of several crop and other plant species to take up prions via their roots and translocate them to above-ground tissues from various growth media including soils. We demonstrate that plants can accumulate prions in above-ground tissues to levels sufficient to transmit disease after oral ingestion. Our results suggest plants may serve as vectors for prion transmission in the environment—a finding with implications for wildlife  conservation, agriculture, and public health

Survival mechanisms of remnant northern long-eared bat (Myotis septentrionalis) populations

Investigators: Wendy Turner, USGS, University of Wisconsin-Madison and Ing-Nang Wang, University at Albany 

Funding: US Fish and Wildlife Service

Completed Date: July 31, 2021

The northern long-eared bat (Myotis septentrionalis, MYSE) is one of the species most affected by white-nose syndrome (WNS), leading to its federal listing in 2015 as Threatened under the Endangered Species Act. Our recent work provides evidence that MYSE populations off the coast of the northeastern US are infected with Pseudogymnoascus destructans (Pd), the causative agent of WNS, and yet these populations are persisting. This project investigated the mechanisms that allow for the persistence of coastal MYSE populations, while populations elsewhere have experienced drastic declines. We hypothesized that availability of abundant anthropogenic hibernacula and the ability to forage in milder winter weather may allow MYSE to reduce Pd exposure and/or WNS infection severity. Our study was replicated on three coastal islands: Long Island, New York, and Martha’s Vineyard and Nantucket, Massachusetts. The project objectives were to i) assess coastal MYSE fall and winter behavior, and identify and characterize coastal hibernation locations, ii) evaluate Pd exposure and infection load of coastal MYSE and their hibernacula, iii) determine winter activity patterns of coastal MYSE and assess prey availability, and iv) investigate the genetic structure of coastal MYSE and compare with the mainland population. A total of 69 MYSE were captured and 54 radio-tagged at 20 capture locations across all three study sites. Bats were tracked daily, resulting in 88 roosts and 15 hibernacula documented. Final Pd testing and bat genetic sequencing results are expected in the next few months.