A new multiplexed magnetic capture—Droplet digital PCR tool for monitoring wildlife population health and pathogen surveillance

Abstract

Anthropogenic stressors are exacerbating the emergence and spread of pathogens worldwide. In regions like the Arctic, where ecosystems are particularly susceptible, marked changes are predicted in regional diversity, intensity, and patterns of infectious diseases. To understand such rapidly changing host‐pathogen dynamics and mitigate the impacts of novel pathogens, we need sensitive disease surveillance tools. We developed and validated a novel multiplexed, magnetic capture, and ddPCR tool for the surveillance of multiple pathogens in polar bears, a sentinel species that is considered susceptible to climate change and other stressors with a pan‐Arctic distribution. Through sequence‐specific magnetic capture, we concentrated five target template sequences from three zoonotic bacteria (Erysipelothrix rhusiopathiae, Francisella tularensis, and Mycobacterium tuberculosis complex) and two parasitic (Toxoplasma gondii and Trichinella spp.) pathogens from large quantities (<100 g) of host tissue. We then designed and validated two multiplexed probe‐based ddPCR assays for the amplification and detection of the low‐concentration target DNA. Validations used 48 polar bear tissues (muscle and liver). We detected 14, 1, 3, 4, and 22 tissue positives for E. rhusiopathiae, F. tularensis, M. tuberculosis complex, T. gondii, and Trichinella spp., respectively. These multiplexed assays offer a rapid, specific tool for quantifying and monitoring the changing geographical and host distributions of pathogens relevant to human and animal health.

The geographic distribution, and the biotic and abiotic predictors of select zoonotic pathogen detections in Canadian polar bears

“…The methods for the tissue preparation, assay design and execution are detailed in Tschritter et al 9 . In brief, a multiplexed magnetic-capture step was used to concentrate target DNA from large quantities of host-tissue with biotinylated capture-oligonucleotides specific to our target sequences.…”

“…To better understand and potentially mitigate the effects of novel and emerging pathogens, we need more information on existing geographic distributions and how changes in climate and other anthropogenic stressors may impact them. Monitoring vast and remote regions like the Arctic is economically and logistically challenging; thus, harvest-based monitoring of pathogen occurrences in sentinel species may offer a cost-effective framework for disease surveillance 9 .…”

“…Here, we survey these five zoonotic pathogens in polar bears from across the Canadian Arctic using a novel multiplexed magnetic-capture and ddPCR tool 9 . We first map the geographical distribution of detections for each pathogen across the Canadian Arctic.…”