The chemical compounds in lichens have long been known to have antibiotic and antiviral properties. Pharmaceutical companies have been studying these properties for years. But recently, scientists from the U.S. Geological Survey’s National Wildlife Health Center found that those same compounds can break down the infectious proteins that cause chronic wasting disease, a devastating neurological disease fatal to moose, elk, and deer.
First identified in the 1960s and detected in 19 states (including New York) and two Canadian provinces, chronic wasting disease is caused by abnormal prions, which are proteins that cause lesions in the animals’ brains. While there is no evidence that chronic wasting disease has ever infected people, hunters, biologists, and naturalists are concerned that the disease could have a devastating effect on the deer herd. The disease-causing prions are notoriously difficult to kill, and once in an environment, they can remain infectious for decades.
Lichenologist Jim Bennett and molecular biologist Christopher Johnson, who share an office at the National Wildlife Health Center, wondered if the antibiotic and antiviral chemicals in lichens might affect prions. They made extracts from dozens of species of lichen and put each one in a test tube with the prions. About 30 percent of the lichens they tested showed anti-prion activity. “We picked the easiest species to collect,” said Bennett. “After an extract worked, we tried putting pieces of lichen tissue in the test tubes, and that worked, too.”
Bennett said that some lichen species contain an enzyme that is capable of significantly breaking down the prions and making them inactive. “This work is exciting because there are so few agents that degrade prions, and even fewer that could be used in the environment without causing harm,” he said.
But whether lichens are useful in combating chronic wasting disease or other prion diseases is still uncertain. Bennett said that his lab is now feeding lichens to mice infected with prion diseases to see if it cures them. He is also studying where in the lichens the chemicals are found and whether those compounds are also in the soils where the lichens live.