[Early intervention of BK virus replication promotes stabilization of renal graft function].

Objective: To investigate the optimal time window for intervention of BK virus (BKV) replication and its effect on the outcomes of kidney transplant recipients (KTRs).

Methods: A retrospective analysis of the clinical data and treatment regimens was conducted among KTRs whose urine BKV load was ≥1.0×10 copies/mL following the operation between April, 2000 and April, 2015. KTRs with urine BKV load <1.0×10 copies/mL matched for transplantation time served as the control group.

Results: A total of 54 recipients positive for urine BKV were included in the analysis. According to urine BKV load, the recipients were divided into 3 groups: group A with urine BKV load of 1.0×10-1.0×10 copies/mL (n=22), group B with urine BKV load >1.0×10 copies/mL (n=24), and group C with plasma BKV load ≥1.0×10 copies/mL (n=8); 47 recipients were included in the control group. During the follow-up for 3.2-34.5 months, the urine and plasma BKV load was obviously lowered after intervention in all the 54 BKV-positive recipients (P<0.05). Eighteen (81.82%) of the recipients in group A and 19 (79.17%) in group B showed stable or improved estimated glomerular filtration rate (eGFR) after the intervention; in group C, 4 recipients (50%) showed stable eGFR after the intervention. In the last follow-up, the recipients in groups A and B showed similar eGFR with the control group (P>0.05), but in group C, eGFR was significantly lower than that of the control group (P=0.001). The recipients in group A and the control group had the best allograft outcome with stable or improved eGFR.

Conclusion: Early intervention of BKV replication (urine BKV load ≥1.0×10 copies/mL) in KTRs with appropriate immunosuppression reduction can be helpful for stabilizing the allograft function and improving the long-term outcomes.