One of them, a densovirus, belongs to a class of viruses associated with deadly epidemics in shrimp, cockroaches, crickets, moths, crabs, and silkworms. It was much more likely to be present in diseased mussels and at higher densities than in healthy controls.
“We used to throw our hands up,” said Tony Goldberg, a veterinary epidemiologist at the University of Wisconsin and co-author. “Now we have a clear hypothesis.”
The results inconclusive show that the virus leads to death. Other factors – bacteria, invasive mussels, warming water – could interact with the novel virus to weaken or kill freshwater mussels.
Next, the Wisconsin researchers will isolate and study the novel virus in a laboratory and eventually use it to experiment on thousands of tiny live clams from hatcheries. Further down, they could even develop a rapid test to detect the virus in cultivated or wild clam populations. However, there are major obstacles to studying the mussels.
Unlike humans, chimpanzees, or even oysters (where there is a financial or humanitarian drive for this type of virology), researchers don’t have an established model for working with freshwater clam cells. That said, they don’t have a clear picture of how mussel cells or the virus are supposed to grow in a laboratory.