Mysterious Wasting Disease in Starfish Examined with Immune Response

Sea stars are dying all along the West Coast. Now, scientists have taken a closer look at the starfish in order to better understand its immune response and its ability to protect a diverse coastal ecosystem.

In this case, the researchers looked at the wasting disease responsible for the largest die-off of sea stars ever recorded. Currently, scientists believe that wasting disease is a virus related to rabies. When infected by the virus, the starfish's arms contort and develop white lesions. Then the normally rigid stars begin to melt and become squishy in the final stages.

Wasting disease impacts nearly 20 different species. In fact, it has caused up to almost 90 percent morality in some areas off the West Coast over the last two years.

"The sea stars protect the rocky shores, keeping them from becoming dominated by mussels," said Lauren Fuess, one of the researchers, in a news release. "When you remove the sea stars, you see dramatic declines of other species, so basically you go from a diverse ecosystem to a mussel-coated beach."

In this latest study, the researchers looked at transcriptomes, or the molecules expressed from the genes of sea stars infected with wasting disease. The researchers found that the sea stars have an immune response that is characterized by various types of immunities and that they have multiple aspects of the toll-signaling pathway, which is an important recognition. The researchers also found several changes in the extra cellular matrix and collagen gene associated with the disease.

"Genes that degrade collagen, which is a component of the sea stars' structure, were being increased in the stars we studied," said Fuess. "So, you have more degradation of that essential collagen and breakdown of the matrix that is used for their movement and rigidity. We also saw changes in nervous genes that might be contributing to that twisting of the arms."

The findings reveal a bit more about this disease, which could be crucial for better understanding it and developing a way to prevent its spread.

The findings are published in the journal PLOS One.

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