INTRODUCTION: Reactivation of BK infection occurs in immunocompromised hosts causing tubulointerstitial nephropathy (BKVN). Approximately 5% of kidney transplant recipients (KTR) develop BKVN, special half of whom lose their grafts. However, BKVN morphologic diagnosis on a renal biopsy is complicated, because the cytopathic changes can sometimes mimic rejection. Thus, BKV DNA-polymerase chain reaction (PCR) assay on serum, urine, and renal tissue is useful for early detection and monitoring of BKV. MATERIALS AND METHODS: We performed routine monthly urine cytologies looking for decoy cells as a marker of virus replication. Then, we performed a qualitative PCR on urine and serum in all recipients (independently of positive or negative cytology). We amplified 3 BK viral genome regions, LT (early transcription region) and VP1 (late transcription region) seeking a more accurate virus detection, and the TCR (control transcription region) region to perform a polymorphism sequence analysis to identify the BK genomic variant. Finally, the BKVN diagnosis was confirmed using renal biopsy. RESULTS: At present, 132 patients have been monitored. Thirteen of 40 (33%) were PCR-urine-positive cases (5 LT+/VP1- and 8 LT+/VP1+), and 10 of 132 (7.5%) were PCR-serum-positive cases (7 LT+/VP1- and 3 LT+/VP1+). When we compared PCR-urine and cytology results, 11 of 40 (27.5%) patients showed a positive cytology, 6 of whom were PCR- urine-positive (1 LT+/VP1- and 5 LT+/VP1+); whereas, 29 patients showed a negative cytology, 7 of whom were PCR-urine-positive(3 LT+/VP1- and 4 LT+/VP1+). Thus, comparison of PCR- urine and cytology results revealed false-positive and false-negative cases. Finally, TCR sequence analysis was performed in 9 patients to identify the BK genomic variants. CONCLUSION: Testing for BKV DNA in urine and serum is a noninvasive early detection assay and monitoring tool.
INTRODUCTION: Reactivation of BK infection occurs in immunocompromised hosts causing tubulointerstitial nephropathy (BKVN). Approximately 5% of kidney transplant recipients (KTR) develop BKVN, special half of whom lose their grafts. However, BKVN morphologic diagnosis on a renal biopsy is complicated, because the cytopathic changes can sometimes mimic rejection. Thus, BKV DNA-polymerase chain reaction (PCR) assay on serum, urine, and renal tissue is useful for early detection and monitoring of BKV. MATERIALS AND METHODS: We performed routine monthly urine cytologies looking for decoy cells as a marker of virus replication. Then, we performed a qualitative PCR on urine and serum in all recipients (independently of positive or negative cytology). We amplified 3 BK viral genome regions, LT (early transcription region) and VP1 (late transcription region) seeking a more accurate virus detection, and the TCR (control transcription region) region to perform a polymorphism sequence analysis to identify the BK genomic variant. Finally, the BKVN diagnosis was confirmed using renal biopsy. RESULTS: At present, 132 patients have been monitored. Thirteen of 40 (33%) were PCR-urine-positive cases (5 LT+/VP1- and 8 LT+/VP1+), and 10 of 132 (7.5%) were PCR-serum-positive cases (7 LT+/VP1- and 3 LT+/VP1+). When we compared PCR-urine and cytology results, 11 of 40 (27.5%) patients showed a positive cytology, 6 of whom were PCR- urine-positive (1 LT+/VP1- and 5 LT+/VP1+); whereas, 29 patients showed a negative cytology, 7 of whom were PCR-urine-positive(3 LT+/VP1- and 4 LT+/VP1+). Thus, comparison of PCR- urine and cytology results revealed false-positive and false-negative cases. Finally, TCR sequence analysis was performed in 9 patients to identify the BK genomic variants. CONCLUSION: Testing for BKV DNA in urine and serum is a noninvasive early detection assay and monitoring tool.