Thursday, May 11, 2006

How HIV can sabotage human cells - BBC news Online

Mammalian ribosome
Ribosomes interpret the genetic code
Scientists have learned more details of the process which turns human cells into factories for viruses such as HIV.

It is known that viruses are able to hijack the genetic machinery of cells for their own ends.

Teams from Cambridge and Oxford Universities have witnessed the process in action, and have identified the crucial role of key elements.

The study, published in Nature, may eventually lead to new treatments for HIV, and other infections.

Very many years of further research would be needed before this research finding will benefit HIV-positive patients
Christopher Gadd

Genes provide cells with a code which they use to manufacture the proteins needed to replicate themselves.

The latest study shows how viruses like HIV are able to undermine this process.

As a result, cells misread the genetic code and instead of producing healthy new cells, they begin to produce new copies of the virus.

Misreading

The process which the viruses employ is known as ribosomal frameshifting. The ribosome is the structure within the cell where protein synthesis takes place.

The genetic code contained in the DNA is read by ribosomes in chunks of three individual components.

The researchers have shown that viruses such as HIV have signals that force the ribosome to back up by just one component.

This is enough to produce a completely different sequence of genetic chunks - and results in the cell beginning to produce proteins that the virus can use to reproduce itself.

The researchers were able to capture images of frameshifting in action using electron microscopy.

Researcher Dr Ian Brierley said the work might prove useful in designing new ways to combat viruses such as HIV which deploy this line of sabotage.

He said: "Other researchers have shown that inhibition of frameshifting can block HIV replication; these new images improve our understanding of frameshifting which might contribute to the design of antiviral strategies."

Professor Julia Goodfellow, of the Biotechnology and Biological Sciences Research Council, which part-funded the study, said: "The treatments and therapies that we now take for granted are based on decades of work by scientists furthering our understanding of natural processes.

"The work to explore fundamental biology today is laying the foundation for potential medical applications over the next 20 years."

Christopher Gadd, of the HIV information service NAM, said the latest research had been carried out not on HIV, but on the virus that causes the respiratory condition Sars.

He said: "This process may eventually become a target for research into new HIV drugs.

"But after over 20 years of the epidemic, the 20 anti-HIV drugs currently licensed only target three different sites in the virus's life cycle.

"Although drugs targeting other parts of HIV's life cycle may be only a few years away, very many years of further research would be needed before this research finding will benefit HIV-positive patients, if at all."

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