Squalamine, an immune agent discovered in sharks and later synthesized in the laboratory, looks to have unusual antiviral properties that researchers hope to harness for human use, according to a Georgetown University Medical Center study.

In tissue culture and animal testing, squalamine has been shown to be effective against a wide range of viral diseases, including hepatitis B, C and D, dengue and yellow fever. As the drug’s safety has already been established in clinical trials for cancer and eye disorders, researchers hope that it can be fast-tracked for antiviral trials in humans.

“To realize that squalamine potentially has broad antiviral properties is immensely exciting, especially since we already know so much from ongoing studies about its behavior in people,” said lead author Michael Zasloff, MD, PhD, professor of surgery and pediatrics at Georgetown University Medical Center and scientific director of the Georgetown Transplant Institute.

Squalamine functions by entering specific kinds of cells—such as those in the liver or blood vessels such as capillaries—and adding a positive electrical charge to the inner membrane. This forcibly detaches other positively charged proteins from the membrane, including proteins viruses use to replicate, effectively neutralizing the virus and killing infected cells.

The study authors believe that because squalamine blocks infection overall rather than attacking specific viral proteins, it’s less likely to generate drug-resistant viral strains.

“We have not yet optimized squalamine dosing in any of the animal models we have studied and as yet we do not know the maximum protective or therapeutic benefit that can be achieved in these systems,” Zasloff said. “But we are sufficiently convinced of the promise of squalamine as an antiviral agent that we intend to take this compound into humans. It is clearly a promising drug, and is unlike, in its mechanism of action and chemical structure, any other substance currently being investigated to treat viral infections.”