Common Childhood Virus That Many Assumed to be Harmless Found to Trigger Bladder Cancer Later in Life!
Kittisak Meepoon Fact checked by:Thailand Medical News Team Dec 04, 2025 2 hours, 31 minutes ago
Medical News: Researchers Discover Surprising Cancer Trigger from Early Infection
A common virus that most people get during childhood and often assume to be harmless is now being linked to a potentially deadly disease later in life. New findings from researchers at the University of York-UK have shown that the BK virus (BK polyomavirus or BKPyV), which typically remains dormant in the kidneys, actually causes the kind of DNA damage that triggers bladder cancer. This
Medical News report uncovers how the body’s own immune defense might ironically be the culprit behind such long-term cancer risks.
A once harmless childhood virus is now found to trigger DNA damage linked to bladder cancer years later
A Closer Look at the BK Virus and DNA Damage
The research team, led by Dr. Simon Baker, used human urinary tract tissue to explore how the body responds to the BK virus. They found that while the body tries to fight off the virus using special enzymes, these same enzymes sometimes cause accidental harm to the person’s own DNA. This process leads to mutations—small changes in genetic material—that may eventually develop into bladder cancer. What makes this even more alarming is that the virus doesn't need to directly infect every cell to cause damage. Neighboring “bystander” cells also suffer genetic injuries due to chemical signals sent during infection. This could explain why many bladder cancer tumors do not show any trace of the BK virus when diagnosed, often years later.
A Silent Risk for Transplant Patients
The BK virus usually causes no symptoms and remains hidden in the body. But it can reactivate in individuals who have weakened immune systems, such as kidney transplant patients who take immunosuppressant drugs. One such patient, Tim Tavender from Southampton, developed both a BK virus infection and later bladder cancer after his 2015 kidney transplant. He described the experience as terrifying. At one point, blood in his urine alerted him to a serious issue—leading to the discovery of his cancer. His surgery took over 13 hours, but he now lives cancer-free. Tim said, “If scientists can find ways to control this virus, it could spare others from what I went through.”
How the Virus Causes Cancer Without Being Found in Tumors
The study explained a new concept called “transmutagenesis.” In this process, the virus doesn’t directly transform a healthy cell into a cancerous one. Instead, it infects nearby cells and triggers a strong immune response. This immune reaction—especially involving substances called interferons—activates enzymes called APOBEC3 that mistakenly damage the DNA of surrounding uninfected cells.
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This model explains how APOBEC3 activity may trigger bladder cancer in a virus-infected environment. Persistent BK polyomavirus in kidney tubules can reactivate and release infected “decoy cells” into urine, which then infect the bladder lining. As the virus begins producing new particles, the bladder expels infected cells marked by VP1. During this extrusion process, nearby cells respond to interferon signals by activating APOBEC3A, which damages DNA. Repeated bursts of BKPyV infection create cycles of APOBEC3A/B activity that gradually accumulate mutations, including uracil lesions that persist until the cell divides. Over time, this can initiate tumors defined by APOBEC3A/B mutational patterns, even though the virus is absent in the final cancer.
Over time, these DNA errors pile up and may lead to cancer. Dr. Baker emphasized that this discovery reshapes the way scientists think about bladder cancer. “We now see how a virus can cause cancer even when it’s no longer in the tissue. The damage is already done long before the tumor appears.”
New Hope for Prevention and Early Screening
Currently, the main advice to prevent bladder cancer is to stop smoking. But this new research opens the possibility of preventing some cases by identifying and controlling the BK virus early. There are no approved treatments or vaccines for BK virus yet, but the researchers are already working on ways to develop antiviral tools. The study also suggests that transplant patients—already at higher risk—could benefit from more focused monitoring for BK virus activity and its effects. In conclusion, while the BK virus may seem harmless in childhood, it holds the potential to quietly set the stage for cancer decades later. Recognizing and addressing this invisible threat early could help save lives in the future.
The study findings were published in the peer reviewed journal: Science Advances.
https://www.science.org/doi/10.1126/sciadv.aea6124
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Medical News.
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