BK viral infection in an Australian pediatric renal transplant population

BK virus (BKV) is recognized as a significant cause of renal allograft dysfunction in adults, and there is growing awareness of its importance in the pediatric population. Eighteen pediatric renal transplant recipients and 18 age-matched controls were prospectively studied. Anti-BKV immunoglobulin G (IgG) and IgM titres were assayed in all subjects at entry to the study. Polymerase chain reaction (PCR) for BKV DNA was performed on urine and serum at entry, and prospectively tested again at 4, 8 and 12 months. Mean age +/- s.d. of transplant recipients and controls was 14.6 +/- 3.3 and 13.9 +/- 0.33 yr respectively [not significant (NS)]. Transplant patients were studied at a mean time of 5.6 +/- 4.2 yr post-transplant. 56% of transplant patients and 39% of controls were seropositive (+ve BKV IgG) (NS). Plasma BKV PCR was positive in one transplant patient (who also had positive urine PCR) and in none of the controls. The prevalence of positive urine PCR in transplant patients was greater than in controls (33% vs. 0%, p = 0.02). Positive urine BKV PCR was more commonly found in patients treated with mycophenolate than azathioprine (p = 0.04). We conclude that the prevalence of BKV seropositivity and viral activation in this Australian pediatric renal transplant population is similar to that reported in adult and pediatric populations in other countries. BK viruria was more common in children with greater immunosuppression, suggesting that this group is at higher risk of BKV induced nephropathy.