by Mike Andrew - SGN Staff Writer

Nanoparticles carrying a toxin found in bee venom can destroy HIV while leaving surrounding cells unharmed, scientists at the Washington University School of Medicine in St. Louis say. Their study has been published in the current issue of the journal Antiviral Therapy.

The study suggests that the bee venom can be loaded onto nanoparticles that are then suspended in a gel and applied topically to prevent HIV infection.

'Our hope is that in places where HIV is running rampant, people could use this gel as a preventive measure to stop the initial infection,' said Dr. Joshua L. Hood, one of the researchers.

In addition to antiviral therapy, the paper's senior author, Dr. Samuel A. Wickline, says that the bee venom can be effective in killing tumor cells.

PROTECTIVE BUMPERS
Bee venom contains a potent toxin called melittin that can poke holes in the protective envelope that surrounds HIV and other viruses. That toxin might also harm normal cells, but Hood added what are described as 'protective bumpers' to the nanoparticle surface.

When the nanoparticles come into contact with normal cells, which are much larger in size than viruses, the particles simply bounce off. HIV, on the other hand, is even smaller than the nanoparticle, so HIV fits between the bumpers and makes contact with the surface of the nanoparticle, where the bee toxin awaits.

'Melittin on the nanoparticles fuses with the viral envelope,' Hood explained. 'The melittin forms little pore-like attack complexes and ruptures the envelope, stripping it off the virus.'

According to Hood, the advantage of this approach is that the nanoparticle attacks an essential part of the virus's structure. In contrast, most anti-HIV drugs inhibit the virus's ability to replicate, but this anti-replication strategy does nothing to stop initial infection, and some strains of the virus have adapted to common drugs and reproduce anyway.

'We are attacking an inherent physical property of HIV,' Hood said. 'Theoretically, there isn't any way for the virus to adapt to that. The virus has to have a protective coat, a double-layered membrane that covers the virus.'

OTHER POSSIBLE USES
Hood says melittin could also be used as therapy for existing HIV infections, especially those that are drug-resistant. The nanoparticles could be injected intravenously and, in theory, would be able to clear HIV from the blood stream.

'The basic particle that we are using in these experiments was developed many years ago as an artificial blood product,' Hood said. 'It didn't work very well for delivering oxygen, but it circulates safely in the body and gives us a nice platform that we can adapt to fight different kinds of infections.'

Since melittin attacks viral membranes indiscriminately, this concept is not limited to HIV. Many viruses, including hepatitis B and C, rely on the same kind of protective envelope and presumably would be vulnerable to melittin-loaded nanoparticles.

Hood added that the nanoparticles are easy to manufacture in large enough quantities to supply them for future clinical trials.

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