London: Researchers have used a library of DNA to create a vaccine that could be used to treat cancer.
Earlier, ``gene therapy`` vaccines have often delivered just one gene to stimulate the immune system. It produces a protein, called an antigen, which activates the immune system to destroy cancer cells.
But now, University of Leeds researchers, working with the Mayo Clinic in Rochester, US, have solved this problem in experiments involving mice.
The team used doses of a vaccine made from a virus, which contained a ``library`` of DNA, containing multiple fragments of genes and therefore many possible antigens. This approach did not send the immune system into overdrive, which had been a concern. Instead the range of DNA meant the vaccine was able to target the tumour through many routes.
Importantly, the DNA library was harvested from the same organ as the tumour. This meant that the immune system ``self-selected`` the cancer antigens to respond to and did not react against other healthy parts of the body. Also, the process of self-selection was triggered when the vaccine was injected into the bloodstream, an approach to vaccination that is far more practical than injecting directly into tumours.
The researchers delivered a library of DNA taken from healthy prostate tissue in mice. When delivered in a virus, the vaccine successfully treated mice with prostate cancer.
University of Leeds`` Professor Alan Melcher, co-author of the study, said: "This is the first time we``ve been able to use a whole library of DNA in a viral vaccine successfully.
"The biggest challenge in immunology is developing antigens that can target the tumour without causing harm elsewhere.
"By using DNA from the same part of the body as the tumour, inserted into a virus, we may be able to solve that problem,” added Melcher.
Researchers made the vaccine by putting the DNA library inside a vesicular stomatitis virus (VSV), which stimulates an immune response that can then track down and kill tumour cells.
The study has been published in Nature Medicine.