Recurrent Nephropathy among Immunocompromised Persons could Warrant BK Polyomavirus Testing

Abstract

Dear Editor,
BK virus (BKV) is a naked DNA virus, which belongs to the Polyomaviridae family. BK and JC polyomaviruses were the first human polyomaviruses isolated from immunosuppressed patients.[1,2] BKV was first isolated in 1971 from the urine of an immunocompromised renal transplant patient with the initials B.K.[2] BKV causes interstitial nephritis in kidney transplant patients but has also been reported to cause renal diseases in nonrenal transplant patients and bone marrow transplant recipients.[3] The BKV seroprevalence stood as high as 81%, with the virus in latent/dormant stage embedded in the urothelium.[4] Intermittent reactivation with low-level viruria (106  virus copies/mL of urine) has been noted in approximately 5% of immunocompromised patients without clinical consequence.[5] Due to the detection of viral DNA in tonsillar tissue, BKV transmission is thought to occur via a respiratory route.[6] There is also evidence for other possible routes of transmission such as fecal-oral, urino-oral, transplacental, and blood transfusion.[6] There are four BKV genotypes: designated I, II, III, and IV. After primary infection, BKV enters a latency phase and tends to persist indefinitely.[7] Autopsy studies have detected BKV mainly in kidney parenchyma, renal pelvis, ureter, and urinary bladder of immunocompetent individuals.[7] Reactivation of BKV replication is observed in states of relative or absolute immunodeficiency such as transplantation, pregnancy, diabetes, cancer, HIV infection, and systemic lupus erythematosus. Unchecked BKV replication can then lead to BKV nephropathy (BKVN) and other organ diseases. 

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