“Detecting the myxozoan parasite Tetracapsuloides bryosalmonae though highly invasive dreissenid mussels (7368)”

Detecting the myxozoan parasite Tetracapsuloides bryosalmonae though highly invasive dreissenid mussels

Introduction
The Great Lakes watershed was recently invaded by Zebra (Dreissena polymorpha) and Quagga (D. bugensis) mussels. Reproducing and growing fast, they became widespread across large and small lakes and rivers in North America, altering ecosystems and threatening local freshwater fisheries. Dreissenid mussels may bio-accumulate substances and microorganisms that could become harmful for animals and people relying on impacted freshwater ecosystems. The myxozoan Tetracapsuloides bryosalmonae (Malacosporea) propagates through a two-host lifecycle and may cause Proliferative Kidney Disease (PKD) in salmonids. Infected freshwater bryozoans, moss filter-feeding organisms, release waterborne malacospores that can be infectious to susceptible salmonids. We recently confirmed the presence of T. bryosalmonae in several salmonid species and bryozoans across the Great Lakes region.
Methodology
Zebra and Quagga mussels were collected from rivers and lakes around Michigan, to assess whether they may be acting as vectors or paratenic hosts for T. bryosalmonae. Whole organisms and selected internal organs (e.g., gills, digestive glands) were screened for T. bryosalmonae detection by PCR, targeting the malacosporean 18S rDNA, followed by histological evaluation of relevant samples.
Results
Dreissenid mussels were often found sharing the same substrates with several bryozoan species, which also grow on their shells. Zebra mussels from distinct locations were found positive to T. bryosalmonae. At least in one instance, this kind of detection allowed the discovery of the parasite presence in a new lake in Michigan, from which no fish samples were available.Conclusions
Defining the possibility of detecting myxozoan parasites from highly invasive filter-feeder shellfish, which are much easier to collect than bryozoans, will determine if they could be used as bioindicators to help detect this regulatory fish pathogen. Defining how myxozoans interact with dreissenid mussels may provide further insights on how the parasite life cycle may be completed.

1. Ahmad Ali, Suhaylah, Fish Pathobiology and Immunology Laboratory, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA, Author
2. Fusianto, Cahya K., Fish Pathobiology and Immunology Laboratory, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA, Author
3. Buszkiewicz, John, Michigan Department of Natural Resources, Waterford, MI, USA, Author
4. GORGOGLIONE, BARTOLOMEO, Fish Pathobiology and Immunology Laboratory, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA, Presenter