Clinical diagnosis of BK virus infection in renal transplant recipients and influence of the immunosuppressive protocol on BKV replication

Abstract

Objective To investigate the methods for clinical diagnosis of BK virus (BKV) infection and to analyze the influence of immunosuppressive protocol on BKV activation in renal transplant recipients. Methods 200 renal recipients receiving renal transplantation during 1999. 1-2007. 1 were selected as objectives, among which, 100 cases subject to FKS06 + MMF protocol were regarded as the intensive observation group; with different immunosuppressive protocol, but the same age and the occurrence of the acute rejection as those of the intensive observation group, the other 100 recipients served as control observation group. 15.3 months, on the average after kidney transplantation,the urine and peripheral blood (PB) samples of 200 renal transplant recipients were taken for the BKV cytological test of urinary sediment and real-time PCR for BKV DNA of both urine and PB in order to analyze the relationship among the amount of decoy cells in urine, the BKV load in urine and the BKV load in PB and compare the positive rate of urine decoy cell, BKV viruria and viremia between the above two groups. Results The positive rate of urine decoy cell, BKV viruria and viremia in all patients were 34%, 36% and 16%, respectively. The amount of deooy cells in urine samples was related to the BKV load in urine samples (r=0.714, P＜0.001), but the BKV load in urine samples was not related to that in PB samples (P=0.14). The positive rate of urine decoy cell, BKV viruria and viremia in the intensive observation group were 49%, 50% and 24%, and in control observation group 19%, 22% and 9%, respectively, with the difference being significant between two groups.Conclusions Urine cytology is very convenient, useful and sensitive for the evaluation of BKV replication. Also BKV DNA detection in the urine and peripheral blood is important to screen the evidence of BK reaction further in order to prevent irreversible graft damage of BKVAN. Using FK506 + MMF can increase the infection rate of BKV in renal transplant recipients, and intensively BKV monitoring is necessary for these recipients. Key words: Kidney transplantation; BK virus; Infection; Decoy cells