Frequency of Polyomavirus BK Infection in Kidney Transplant Patients Suspected to Nephropathy

BACKGROUND: Polyomavirus BK is a major cause of nephropathy in immunosuppressed transplanted patients. Non-invasive diagnostic protocols such as molecular detection of polyomavirus BK replication are a useful strategy to predict BK virus-associated nephropathy (BKVAN). OBJECTIVE: To determine the prevalence of polyomavirus BK infection among kidney transplant patients suspected to have BKVAN. METHODS: In a cross-sectional study 108 kidney transplanted patients whose laboratory and clinical presentation were in favor of nephropathy between 2010 and 2012, were enrolled for analysis. Polyomavirus BK replication was evaluated in plasma and tissue samples of studied patients using a quantitative real-time PCR. Active cytomegalovirus infection was analyzed in studied patients using antigenemia method. A possible association between polyomavirus BK infection with clinical and laboratory risk factors of BKVAN were evaluated. RESULTS: The polyomavirus BK replication was found in 17 (15.7%) of 108 of plasma and 9 (11%) of 82 tissue samples in kidney transplanted patients. Cytomegalovirus co-infection was found in 3 of 17 and 3 of 9 plasma and tissue samples in polyomavirus BK infected patients, respectively. Significant associations were found between polyomavirus BK infection with tubulointerstitial nephritis and acute cellular rejection, as important pathologic findings of BKVAN. CONCLUSION: Diagnosis of single and co-infection of polyomavirus BK infection in plasma samples is a useful assay to evaluate the risk of BKVAN in kidney transplant patients. Established threshold values for studied viral infections have beneficial use in screening of kidney transplant patients at risk of BKVAN, need to confirm and standardized in completed further studies.