Polyoma BK virus infection in renal transplant recipients

Several studies reported a correlation between the human Polyomavirus BK (BKV) and interstitial nephritis (PVN: Polyoma Virus Nephropaty) in renal transplant recipients in whom immunosuppressive treatment is thought to facilitate or induce reactivation of the virus. In the present study we monthly evaluated the presence of BKV-DNA in plasma and urine of 29 kidney transplant recipients. We used a nested PCR for BKV-DNA screening in plasma and urine and a quantitative assay Real Time PCR in case of a positive screening result. The viral DNA has been detected in 48% of the patients samples: only in urine of six patients; in plasma of four and in both of two. Immunosuppressive therapy has been decreased in positive patients. The kidney loss occurred just in the two patients with high viral load in plasma and urine. The definitive diagnosis of BKV Nephropaty requires allograft biopsy though biomolecular test for BKV-DNA in urine (viruria) and in plasma (viremia) could be very important non-invasive method for the early diagnosis of PVN.