27 May 2008

Lock HIV in a cage?

The human immunodeficiency virus that causes AIDS, like other viruses, is an intracellular parasite and cannot reproduce without the participation of living cells. Viruses "trick" cell systems in various ways, forcing them to produce viral proteins instead of their own.

The infected cell works as a kind of factory for the production of viral particles – virions, which at the final stage of development must exit through the membrane of the infected cell.

Scientists previously knew that most human cells contain a factor regulating the release of viral particles, but until now this factor has not been identified.

Biologists from the medical schools of Emory University (Georgia), Vanderbilt University and the Mayo Clinic have found that HIV particles are "locked" in cells by the CAML protein (calcium-modulating cyclophilin ligand).

This protein works at the last stage of the virus life cycle by holding virions in the cell membrane. However, HIV has also developed a means of defense against CAML – the viral protein Vpu. If there is no Vpu, virus particles cannot separate from the membrane.

When researchers in the lab "removed" the CAML protein from human cells, they found that Vpu was no longer required for virus particles to escape from the cell. When scientists injected CAML into cells that normally do not prevent the release of HIV particles, the virions remained on the cell surface.

The authors of the study, published in the journal Nature Medicine, believe that their discovery will help create new ways to fight HIV.

"This study is very important because it shows that CAML is an innate defense mechanism against HIV," notes one of the authors, Professor Paul Spearman from Emory University. - "We will continue to investigate the mechanism that uses the Vpu protein to counteract CAML, and to clarify exactly how CAML keeps virus particles on the cell membrane. We hope that this will give us new ways of treatment," he says.

Portal "Eternal youth" www.vechnayamolodost.ru according to the materials of RIA Novosti


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