Clearly, more work with Gd-Tex is necessary, but in our battle to stay one step ahead of the ever-mutating virus, different treatment options are vital

Mark Graver, Terrence Higgins Trust

HIV is so devastating because it takes over and kills a type of blood cell called a CD4+ helper T cells.

CD4+ helper T cells are crucial because they help coordinate the immune defences against foreign invaders such as bacteria.

Without them, HIV patients are vulnerable to a wide range of illnesses.

However, researchers from Stanford University Medical Center have been testing the drug, called motexafin gadolinium (Gd-Tex), on immune cells in the laboratory.

Kill the weakest

They found that, even in low doses, the drug appeared to selectively kill only the cells infected with HIV.

They believe that because the HIV infected cells are already weakened, and the attack from the drug simply "pushes it over the edge" - but spares non-infected cells because they are more resilient.

The lead author of the study, Omar Perez, said: "The first clue that Gd-Tex worked was that the CD4+ T cells were disappearing."

However, it is not yet clear whether the transfer from laboratory to live patient can be made successfully.

In particular, it may be harder to produce a precise level of Gd-Tex in the body than in a test tube.

Risks to patients

And doctors fear that the speedy breakdown of CD4+ T cells could release harmful toxins into the body.

However, the pharmaceutical company which makes Gd-Tex is hoping to begin clinical trials of the drug in HIV patients within the next few months.

A spokesman for the Terrence Higgins Trust said: "It is exciting & interesting that a range of different approaches to HIV treatments such as this one are being tried.

"Clearly, more work with Gd-Tex is necessary, but in our battle to stay one step ahead of the ever-mutating virus, different treatment options are vital."