Shark compound could treat viral infections

A compound found in sharks could potentially be used to treat a range of viral infections, scientists claim.

US researchers said that a naturally occurring cholesterol-like molecule - squalamine - could be used to treat a broad range of viral diseases, from dengue and yellow fever to hepatitis B, C and D.

The compound is already being tested in clinical trials as a potential treatment to slow down blood vessel growth in cancers and eye disorders, and has been shown to be safe to use.

This means that squalamine could quickly be tested as an antiviral agent in humans, researchers from Georgetown University said.

Professor Michael Zasloff, who led the study, said: "I believe squalamine is one of a family of related compounds that protects sharks and some other 'primitive' ocean vertebrates, such as the sea lamprey, from viruses.

“Squalamine appears to protect against viruses that attack the liver and blood tissues, and other similar compounds that we know exist in the shark likely protect against respiratory viral infections, and so on.

"We may be able to harness the shark's novel immune system to turn all of these antiviral compounds into agents that protect humans against a wide variety of viruses.

"That would be revolutionary. While many antibacterial agents exist, doctors have few antiviral drugs to help their patients, and few of those are broadly active."

Professor Zasloff discovered squalamine in 1993, while looking for new antibacterial agents. He was interested in why sharks were so hardy, despite having primitive immune systems.

Since then, the compound has been synthesised in the laboratory, which means scientists don't need to rely on shark tissue for experiments.

In tissue culture studies, squalamine was shown to inhibit the infection of human blood vessel cells by the dengue virus and human liver cells infected with hepatitis B and D, which can cause liver failure and cancer.

Other studies on animals found that squalamine controlled infections of yellow fever, Eastern equine encephalitis virus, and murine cytomegalovirus. In some cases the animals were cured of disease.

Professor Zasloff said that squalamine enters certain types of cells, such as those found in blood vessels, capillaries, and the liver.

The compound appears to displace positively-charged proteins on the cell's membrane, some of which are needed by viruses to multiply. Without them, the viral life cycle is disrupted, and the cell containing the virus is destroyed.

The study was published in the Proceedings of the National Academy of Sciences.

This article was published on Tue 20 September 2011