Live dogfish shark. (Photo: washington.edu)
Shark molecule could cure hard-to-treat viral diseases in humans
Wednesday, September 21, 2011, 03:30 (GMT + 9)
A new study shows that a cholesterol-like compound found in the tissue of dogfish sharks fights multiple tough viruses that plague humans with hard-to-treat diseases.
The potent compound is called squalamine and is already being used in humans without major side effects in clinical trials for cancer and eye disorders.
Squalamine can also act as an antiviral by interrupting a virus's life cycle and keeping it from reproducing in tissue cultures and live animals.
The findings were published this week in the journal Proceedings of the National Academy of Sciences.
"It's a whole new approach to treatment of viral disease," said study leader Michael Zasloff, director of surgical immunology at Georgetown University Hospital's Transplant Institute. "It's very possible we could cure several diseases we [now] treat as chronic infections," National Geographic News reports.
He discovered squalamine in 1993. Sharks are immune to certain diseases and all viruses, and Zasloff observed that the compound inhibits the growth of blood vessels and thus perhaps stop cancer cells from multiplying – and also kill viruses.
"There is no other compound known to science that does this—this is a remarkable property," Zasloff said.
Squalamine could be the secret to sharks’ “very remarkable immune system” and evolutionary success.
Zasloff’s study showed that squalamine disrupted infection of the six viruses, such as dengue fever virus in human blood vessel cells and of hepatitis B and D in human liver cells.
Notably, shark tissue is no longer required to produce squalamine, so the species will not have to suffer for humanity’s benefit. The compound has been synthesized in the laboratory since 1995.
Zasloff and his team also found that squalamine inhibited yellow fever, eastern equine encephalitis virus, and murine cytomegalovirus in lab animals and even cured some subjects.
Adapting squalamine to antiviral drugs "sounds promising" to Todd Rider, a senior staff scientist at the Massachusetts Institute of Technology's Lincoln Laboratory and Division of Comparative Medicine.
"It will be interesting to see what additional viruses squalamine is or is not effective against, and whether the antiviral efficacy can be achieved without toxicity in any type of tissue," Rider said.
Zasloff said, however, that all substances have some toxicity, and that clinical trials will reveal how safe squalamine is for humans. He predicts clinical trials for the antiviral will begin in humans in about a year.
Sharks also carry several other squalamine-like molecules, which work on other tissues and organs.
"I believe that each of those compounds renders those tissues resistant and the day will come when we will be in a position to administer a compound to a human being and render certain organs selectively resistant against particular viruses," Zasloff explained, Live Science reports.
By Natalia Real