Shark Molecule Kills Human Viruses, Too

Posted October 23rd, 2011 by admin
in

A molecule found in sharks appears to be able to wipe out human liver viruses, such as hepatitis, new research has found. 

"Sharks are remarkably resistant to viruses," study researcher Michael
Zasloff, of the Georgetown University Medical Center, told LiveScience.
Zasloff discovered the molecule, squalamine, in 1993 in the dogfish
shark, a small- to medium-size shark found in the Atlantic, Pacific, and
Indian Oceans.

"It looked like no other compound that had been described in any animal
or plant before. It was something completely unique," Zasloff said. The
compound is a potent antibacterial and has shown efficacy in treating
human cancers and an eye condition known as macular degeneration, which
causes blindness.

Zasloff's new research shows it can also kill many human liver viruses,
though a few researchers who weren't involved in the study do have
concerns that in order to see an effect, you'd need toxic levels of the
molecule.

Viral activity

By studying the compound's structure and how it works in the human
body, Zasloff thought it might have some antiviral properties. He saw
that the molecule works by sticking to the cell membranes of the liver
and blood vessels. While there, it kicks off other proteins, some of
which are essential for viruses to enter and survive in the cell.

The researchers decided to test the compound on several different live
viruses that infect liver cells, including hepatitis B, dengue virus and
yellow fever. They saw high efficacy across the board.

The researchers were unable to test the compound against hepatitis C,
a virus that infects the livers of about 1.5 percent of the U.S.
population and can cause liver cancer, because hepatitis C doesn't grow
well in lab models like rats. Yellow fever virus is often used as a
surrogate lab test to show possible efficacy against hepatitis C, and
the researchers were able to cure yellow fever in hamsters with
squalamine.  [7 Devastating Infectious Diseases]

Zasloff hopes to start human trials in the next few years.

Future treatments

The sharks also contain a number of other squalamine-like molecules,
which target other tissues and organs. Some interact with the
respiratory system and others with the kidneys.

"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. Zasloff holds
several patents for the use of squalamine and related compounds for the
treatment of viral diseases.

Jean Michel Brunel, a researcher from the University of the
Mediterranean in Marseille, France, is excited about the data, though he
said the concentrations used to kill the viruses are high, and, as
such, could be toxic to humans.

Marc Maresca, a researcher at Paul Cézanne University in
Aix-en-Provence, France, who wasn't involved in the study, agreed that
the concentrations used were quite high, possibly in toxic ranges for
some cells, but in an email to LiveScience Meresca also called the study
"very exciting."

"Overall, the paper is very convincing," Meresca said. "It could open a
new way to fight against major viruses such as HBV, HCV or HIV."

The study was published today (Sept. 19) in the journal Proceedings of the National Academies of Sciences.