Sea Stars: Researchers Study Immune Response To Deadly Disease

A deadly wasting disease has spread among millions of sea stars living along the U. S. West Coast. Why this disease has affected so many starfish has long troubled scientists. After studying the iconic marine creature's immune system, a group of students now understand how genes behave when encountering this naturally occurring pathogen.

"Doing this study isn't going to save the sea stars, but from an ecological perspective, it provides new information," Steven Roberts, an associate professor at the University of Washington (UW), said in a news release. "This could be a building block for future studies on the evolution of immune repertoires."

Densovirus is the pathogen linked to the deadly starfish disease, which caused a major die-off three years ago and has become too common of a virus among marine ecosystems stretching from Southern California to Alaska. When infected, sea stars develop white lesions on their limbs and within days can dissolve or "melt" into a gooey mass.

To get to the bottom of the problem, a collaborative group of students taking a summer class at UW's Friday Harbor Laboratories looked specifically at how genes expressed themselves in both healthy and sick sea stars. This helps researchers better understand how the sea stars attempt to fight the virus and why they develop lesions.

To prepare for in-the-field tests, UW instructors collected sea stars from four sites in Washington, then infected some with the virus. Then they collected RNA data of each sea star group for students to analyze. This gave them a better idea of how the disease affected the sea stars.

They concluded that sick sea stars expressed genes differently than healthy ones, and infected sea stars also had a genetic immune response, according to the release. Researchers explained that some of the genes involved in the nervous system and tissue building were also expressed differently in sick and healthy sea stars. This could ultimately explain how the disease kills sea stars.

"This gives us a bit of insight into what's going on," Roberts said in a statement. "One could argue that in the long term, this information could be used to build upon."

This recent study led researchers to believe that environmental conditions such as water temperature contribute to how effectively and efficiently sea stars are able to fight off the deadly disease. Conservationists could use this to better protect sea star populations.

Their study was recently published in the journal PLOS ONE.

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