by Tanya Thomas on  November 25, 2008 at 9:14 AM Drug News
 Experimental Drug Holds Key to Tackling New Viruses, Including Bioterror Pathogen
A study has revealed the existence of a new experimental drug which, following several tests on lab animals, has proved its mettle in combating two viruses. One of these viruses is closely related to a potential lethal bioterror pathogen.

The drug, bavituximab, takes a novel tack in confronting viruses, which are notorious for mutations that evade or resist conventional pharmaceutical molecules.

Instead of confronting the intruder head-on, bavituximab waits until the virus has infected the cell.

At that point, a fatty molecule called phosphatidylserine, which is normally positioned on the cell wall's internal surface, flips to the outside of the cell.

Bavituximab then latches onto the phosphatidylserine, sending a red flag to the body's immune system to dispatch white blood cells to destroy the infected cell.

In a study in Nature Medicine, published by the London-based Nature group, bavituximab was put through its paces among guinea pigs infected with Pichinde virus - a close relative of the Lassa fever virus, considered a potential bioterror weapon by the Pentagon.

Animals that had not been inoculated with bavituximab were succumbed to the virus; those who had received the injection had a 50-percent survival rate. By giving the bavituximab group an additional injection with a standard anti-virus drug called ribavirin, the survival rate rose to 63 percent.

The drug also provided 100-percent protection amongst mice exposed to a virus called cytomegalovirus, whereas only 25 percent of untreated animals survived.

Co-author Philip Thorpe, a professor of pharmacology at UT Southwestern Medical Center in Texas, said the findings were exciting, for they raised the prospect of a "completely new class" of anti-viral drugs that may also sidestep the problem of mutation.

"By targeting a property of the host cell rather than the virus itself, anti-PS ie phosphatidylserine antibodies have the potential to treat a range of viral infections," he said in a press release.

"They should be less susceptible to the viral mutations that contribute to the development of drug resistance."

Bavituximab, a monoclonal antibody, is currently in clinical trials by Peregrine Pharmaceuticals Inc. of California to treat patients with hepatitis C.

Previous research has shown that phosphatidylserine-flipping occurs in cells infected with influenza, the herpes simplex virus, viruses in the families of the smallpox and rabies viruses as well as HIV, UT Southwestern Medical Center said.

Source: AFP

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