Welsh scientists have developed cutting-edge "bionic assassins" to seek out and destroy the HIV virus.

A team from Cardiff University has discovered a way to genetically engineer the body's own immune cells in a breakthrough which could revolutionise the treatment of HIV.

Experts at the university also hope that the breakthrough could be applied to cancer by finding a way of using the body's own immune cells to attack invading cancer cells and tumours.

The team's genetically-engineered killer T-cells are able to identify and destroy HIV even when the virus mutates in a bid to avoid detection.

It is thought that the breakthrough could lead to the development of more effective treatments for HIV and could even slow down - or prevent - the onset of Aids.

The researchers are now waiting for final approvals to test the discovery in a series of clinical trails in the US.

The search for a cure or a vaccine for HIV, which has infected 33 million people worldwide, has been hampered by the virus' ability to mutate once inside the body.

When viruses enter our bodies, they hijack host cells in order to replicate and spread infection.

Small parts of the virus usually become exposed on the surface of the cell, creating a "molecular fingerprint" for killer T-cells from the immune system to identify and destroy them.

But HIV can disguise its fingerprints, allowing it to hide from these killer cells, ensuring that the immune system is unable to rid the body of HIV.

Professor Andy Sewell, who co-led the research between Cardiff University, the University of Pennsylvania's School of Medicine and Adaptimmune (corr)Ltd UK , said: "When the body mounts a new killer T-cell response to HIV, the virus can alter the molecular fingerprint that these cells are searching for in just a few days.

"It is impossible to track and destroy something that can disguise itself so readily.

"As soon as we saw, more than a decade ago, how quickly the virus can evade the immune system we knew there would never be a conventional vaccine for HIV."

The international team of scientists have engineered a T-cell receptor which can recognise all of the different disguises that HIV is known to have used to evade detection.

The researchers attached this receptor to the killer T-cells to create genetically-engineered "bionic assassins" able to destroy HIV-infected cells in culture.

But even if the virus is still able to mutate further and avoid being flushed out of the body, every time it is forced to mutate to avoid detection by killer T-cells, it becomes less powerful.

Professor Sewell said: "In the face of our engineered assassin cells, the virus will either die or be forced to change its disguises again, weakening itself along the way.

"We'd prefer the first option but I suspect we'll see the latter. Even if we do only cripple the virus, this will still be a good outcome as it is likely to become a much slower target and be easier to pick off.

"Forcing the virus to a weaker state would likely reduce its capacity to transmit within the population and may help slow or even prevent the onset of Aids in individuals."

Dr Bent Jakobsen(corr), chief scientific Officer at Adaptimmune Ltd, said: "We have managed to engineer a receptor that is able to detect HIV's key fingerprints and is able to clear HIV infection in the laboratory.

"If we can translate those results in the clinic, we could at last have a very powerful therapy on our hands."

The research has been partially funded by the Wellcome Trust and is published online in the journal Nature Medicine.