Projects Completed This Year

Uptake of Prions Into Plants

Investigator:                       Joel Pedersen, Department of Soil Science, University of Wisconsin-Madison

Funding:                             US Geological Survey – National Wildlife Health Center

Expected Completion:        December 31, 2016

Prion-contaminated environments contribute to the maintenance of epizootics of chronic wasting disease (CWD) in deer and elk and scrapie in sheep and goats, yet environmentally mediated routes of disease transmission remain incompletely understood. Existing evidence implicates soil as a plausible environmental reservoir for prion infectivity. We therefore examined the potential for crop and other plant species to mediate prion disease transmission to susceptible hosts. We demonstrate that infectious prion protein can be internalized via plant root structures and translocated to aerial tissues where infectivity accumulates to levels sufficient to cause prion disease in rodent hosts via intracerebral and oral routes of exposure to contaminated plant tissue. We advance the current state of knowledge on prion contamination of plants by demonstrating prion uptake in several crop plant species, from various soil types, and quantify prion loads within contaminated plants (as a first step toward quantitative risk assessment). Plants may serve as a previously unrecognized route of human and animal exposure to prions shed to the environment.

Oral Vaccines and Delivery Methods for Controlling Disease in Bats

Investigators:                      Jorge Osorio, School of Veterinary Medicine, University of Wisconsin-Madison

Funding:                             US Geological Survey (National Wildlife Health Center)

Expected Completion:        June 30, 2017

A new raccoon pox (RCN) vectored rabies vaccine was developed and tested in big brown bats.  This vaccine, delivered either oronasally or via topical application in a glycerin jelly, was highly efficacious in protecting bats against virulent rabies challenge. Several vaccine candidates were also tested for their efficacy in protecting bats against white nose syndrome in little brown bats.  Two of these delivered to bats simultaneously resulted in lower incidence of white nose syndrome.  These constructs will be further tested in future studies. Several pilot studies were conducted to test possible oral delivery methods in little brown bats, both in laboratory and field studies. In the field, bats were captured and glycerin jelly with biomarker was applied to their back and shoulders. Within a week later, they were trapped again to evaluate biomarker uptake and transfer.  We also tested application of the same material (with biomarker) to bat houses, followed by trapping of bats at the house a fed days later. Both methods resulted in high rates of ingestion of the medium by bats as evidenced by the presence of biomarker in their hair. These studies as well as the vaccine efficacy experiments provide proof of concept that mass immunization of bats may be feasible.

The Impact of Sylvatic Plague Vaccine (SPV) Application to Prairie Dog Colonies and Other Small Rodent Populations

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

Funding:                             US Geological Survey – National Wildlife Health Center, U. S. Fish and Wildlife Service

Completion Date:              August 31, 2017

During the 3-year field study no significant effect of the sylvatic plague vaccine for prairie dogs was detected in deer mouse abundance, small rodent evenness and richness. In addition, several plague related question were explored to assess the role of short-lived rodents (e.g. deer mice, grasshopper mice) in plague ecology on the prairie dog colonies.  Most notably, on two prairie dog colonies plague positive mouse fleas were collected from mice prior to a plague outbreak in prairie dogs. This temporal pattern had not been described before and provides some evidence of short-lived rodent involvement in plague ecology on prairie dog colonies.