Researchers have created artificial designer viruses that can stimulate the immune system to specifically combat cancer cells.

These designer viruses alert the immune system and cause it to send killer cells to help fight the tumour, according to a study published in the journal Nature Communications.

Most cancer cells only provoke a limited reaction from the immune system — the body’s defence mechanism — and can thus grow without appreciable resistance.

By contrast, viral infections cause the body to release alarm signals, stimulating the immune system to use all available means to fight the invader.

Immunotherapies have been successfully used to treat cancer for many years; they “disinhibit” the body’s defence system and so also strengthen its half-hearted fight against cancer cells.

Stimulating the immune system to specifically and wholeheartedly combat cancer cells, however, has remained a distant goal.

The innovative designer viruses, manufactured by Swiss scientists from the University of Geneva (UNIGE) and the University of Basel, could do exactly that.

“We hope that our new findings and technologies will soon be used in cancer treatments,” the study authors said.

The researchers built artificial viruses based on lymphocytic choriomeningitis virus (LCMV), which can infect both rodents and humans.

Although they were not harmful for mice, they did release the alarm signals typical of viral infections.

The virologists also integrated certain proteins into the virus that are otherwise found only in cancer cells. Infection with the designer virus enabled the immune system to recognise these cancer proteins as dangerous.

The unique combination of alarm signals and the cancer cell protein stimulated the immune system to create a powerful army of cytotoxic T-lymphocytes, also known as killer cells, which identified the cancer cells through their protein and successfully destroyed them, the study said.