The BK virus leads to a viral infection, but there are no symptoms associated with a BK virus infection. The virus usually remains latent in the body, this has to do with the immune system of the infected person, among other things. With a weak immune system, the infected person is more likely to experience symptoms. Symptoms may include changes in vision, painful urination, difficulty breathing, fever, muscle aches and seizures. When undergoing an organ transplant, an infection from BK virus can also develop. This can potentially lead to serious symptoms, due to the fact that the immune system may be compromised.

Diagnosis of a BK virus is based on the quantitative detection of viral DNA in urine, plasma or other material. BK virus DNA material has been found in the tumors of human brain, pancreatic islets and urinary tract. T-Ag is the antigen encoding tumor antigen and it can bind to the tumor suppressor protein P53. This interaction can be detected by the BK virus PCR kit during detection of the BK virus.