Background: Our study attempts to evaluate the utility of the screening protocol to as a marker of overt immunosuppression as well as any correlation to CMV infection.

Methods: 159 de novo kidney-only recipients were enrolled from January 2011 onwards. Standard immunosuppression with Alemtuzemab or Basiliximab and mycophenolate mofetil (MMF)/FK506 ± prednisone was prescribed. Quantitative BK virus polymerase chain reaction (PCR) surveillance in plasma was performed monthly for the first 6 months then every 3 months for 2 years. Patients with significant viremia (defined as >10,000 gEq/ mL) were treated by stopping MMF and 30% – 60% reduction in doses of FK506 without antiviral therapy. The target 12-hr FK 506 trough levels were lowered to 4 – 5 ng/mL in the significant viremia group, whereas the target levels remained unchanged at 5 – 8 ng/mL for all other groups. The renal biopsy was performed only if renal functions deteriorated despite these measures.

Results: Forty -one (26%) developed BK viremia; 27 (16%) of whom had significant viremia. A total of seven (25%) of the 25 (of 27) patients who underwent biopsy had BKVAN with positive SV 40 staining. The mean plasma BKV PCR reduced by 91% (range, 52%-100%) at 24 weeks after peak viremia. Acute cellular rejection seen in 02 (07%) of 27 patients, responded to bolus steroids. The median FK 506 level in patients with BKVAN was 8.5 ± 1.2 ng/mL. The actuarial graft survival rate in patients with BKVAN was 100%, 98%, 96% and at the death censored graft survival rate was 100%, 100%, 98% at 6, 12, 18 months post renal transplant. There was no significant decline in mean creatinine clearance at 1 month after transplantation to 1 year after peak viremia (P=0.67). There was no statistical correlation in development of significant BK Viremia with CMV infection (p=0.81), Cold Ischemia Time (p=0.06) or Alemtuzemab induction (p=0.09).

Conclusions: BK viremia was controlled with reduction in immunosuppression in majority of patients. Nearly 10% patients had significant viremia, 4.5% patients had BKVAN and 1.2% patients had graft loss in the our screened population. PCR monitoring for BK viremia, together with a protocol decrease in immunosuppression, effectively reduces rates of BKVAN and graft loss. Our BK viremia rate was similar to the majority of published reports.

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