A cholesterol-like compound found in dogfish sharks' tissue has been shown to combat several viruses that cause hard-to-treat human diseases, such as dengue fever and hepatitis, a new study says. (Take a quiz on infectious diseases.)

Called squalamine, the compound is already in human clinical trials for cancer and eye disorders, and several hundred people have been exposed without major side effects.

The new study revealed that squalamine can also disrupt a virus's life cycle and prevent it from replicating in both tissue cultures and live animals.

Though there are plenty of drugs to treat bacterial infections, there are few pharmaceuticals that are effective against viruses. Current antiviral drugs are highly specific—each targeting just one strain of a virus—but strains can easily