A COMMON childhood viral infection causes damage to cells in the bladder which may lead to cancer, a new study has shown.

The study, led by researchers at the University of York and funded by the charity York Against Cancer, used laboratory grown human bladder cells to show that the virus, called BK, could be responsible for patterns of DNA damage seen in bladder tumours.

BK virus infects most people as children and causes cold-like symptoms. The virus can remain hidden in the kidneys and reactivate if the immune system is weakened, the authors of the study say.

The research reveals how reactivation of BK triggers bladder cells to use specialist enzymes to destroy the virus.

Dr Simon Baker, from the Department of Biology at the University of York said: “Our findings alter our understanding of the causes of bladder cancer by showing that BK virus infections are a risk factor for bladder cancer because they force bladder cells to use APOBECs that damage their DNA.”

The main risk factor for bladder cancer is smoking. But, when scientists have examined DNA from bladder tumours, they have not found the patterns of damage they would expect from smoke carcinogens - but damage that has the signature pattern of the APOBECs enzymes.

The full study is published in the journal, Oncogene.