Myxozoan host-sensing in a complex life cycle

Benjamin Americus1, Tamar Lotan2, Jerri L. Bartholomew1, Stephen D. Atkinson1

1Department of Microbiology, Oregon State University, Corvallis, OR; 2Department of Marine Biology, University of Haifa, Haifa, Israel

ABSTRACT

The myxozoans are an anciently derived clade of Cnidaria, related to jellyfish and sea anemones. They are microscopic parasites that utilize vertebrate (fish) and invertebrate hosts, and alternate between two life stages: a fish-infective stage and an invertebrate-infective stage. Ceratonova shasta is native to the Pacific Northwest and infects many species of anadromous salmon including threatened coho in the Klamath River, causing enteronecrosis and death. Tetracapsuloides brysalmonae is an emergent parasite in the Northwest and infects hatchery and wild salmon, causing proliferative kidney disease.

 

Current monitoring techniques for both species use qPCR to detect parasite DNA in water samples and cannot differentiate the two spore stages (only one of which is infectious to fish). To develop more selective assays, we searched for protein targets that are different between the two spore types. We utilized C. shasta and T. bryosalmonae transcriptomes extracted from their respective hosts: Rainbow trout (Oncorhynchus mykiss) the annelid Manayunkia occidentalis, and the bryozoan Fredericella sultana. We identified several genes putatively involved in host-sensing and attachment that are differentially expressed between the two spore forms. These included voltage-gated calcium channels and mechanoreceptors. We are investigating the potential to use these proteins in an assay to differentiate myxozoan spores in environmental water samples and provide better information to fisheries managers.