BKV virus and infection

The BK virus (BKV) is a member of the polyoma subgroup of papovavirus to which group also JC and SV-40 belongs. These are unenveloped double stranded DNA viruses. The name of the virus refers to the initials of the first patient diagnosed with the virus. A primary infection with BKV is most often asymptomatic and occurs during childhood, at a median age of 4-5 years. In adults the seroprevalence is about 75%.

After the primary infection has occurred, the virus can remain latent, most notably in the kidney. However, peripheral blood leukocytes are also proposed sites for latency. In states of immunosuppression the virus can become reactivated and cause disease.

Minor immune impairment can lead to increased viral replication and the presence of the virus in urine. This may occur, in e.g. patients with diabetes and elderly patients. In more severe immune compromised patients, such as AIDS, lymphoproliferative disease or immunosuppressive therapy sometimes results in uncontrolled viral replication leading to damages to involved organs.

The kidney, lung, eye, liver and brain are main sites of BKV disease, both primary and reactivated. The virus is strongly associated with hemorrhagic cystitis and nephritis, encephalitis, especially in kidney transplant recipients or bone marrow transplants recipients.

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