New Delhi, Dec 4
UK researchers have found a common childhood virus that can trigger DNA damage leading to bladder cancer later in life.

Tackling the virus early could open the door to preventing bladder cancer later, said the team from the University of York.

The study, published in Science Advances, revealed that after being contracted in childhood, the BK virus usually lies dormant in the kidney.

BK virus infections do not have obvious symptoms, but physicians have learned a lot about the virus from the experiences of kidney transplant recipients who have to take immunosuppressants to prevent the immune system from targeting their new kidney.

In laboratory studies using the human tissue that lines the urinary tract (urothelium), the team observed DNA damage patterns caused by the cell's antiviral defences after controlled exposure to BK virus -- the childhood infection identified earlier as lying dormant in the kidney.

In this fight against the BK virus, "friendly fire" from enzymes meant to damage the virus can cause collateral damage in the cells' own DNA.

This evidence supports a theory in which an individual's own antiviral response to BK virus infection causes the DNA mutations that can lead to cancer.

"In other types of virus-related cancer, such as cervical cancer, we know that virus DNA combines with our own genetic material to drive tumour development. Our results have shown that in the bladder, the tissue's defensive response to the virus causes DNA changes which can lead to cancer,” said Dr. Simon Baker from the University.

"We found that DNA damage happens not only in infected cells but also in surrounding 'bystander cells,' witnessing infection in their neighbours. This is important because it might explain why most bladder cancers have no sign of the virus in them when they are diagnosed many years later," Baker added.

The BK virus usually lies dormant in the kidney. Immunosuppressants can allow dormant BK virus to reactivate, damaging the kidneys, ureter, and bladder.

Current bladder cancer prevention work asks people to stop smoking. The findings provide a new opportunity to help prevent bladder cancer through the identification and control of the BK virus earlier.

Study links common childhood virus to bladder cancer