Pretransplant serologic testing to identify the risk of polyoma BK viremia in pediatric kidney transplant recipients.

This study investigated the age-related prevalence of a prior polyoma BKV infection at the time of transplantation and association with subsequent development of BKV viremia. We measured BKV-specific antibody titers in stored serum samples obtained before transplantation in 94 pediatric kidney transplant recipients (in a single-center, retrospective analysis) and 40 matched donors from 1986 to 2007. Titers were categorized as LOW or HIGH serostatus at titers of ≤ 1:2560 and ≥ 1:10 240, respectively. Of these, 36 recipients transplanted since 2002 were prospectively screened for BKV viremia. Seventeen percent of recipients aged 0-6 yr had HIGH BKV serostatus compared with 73% of older recipients (p < 0.002). The prevalence of HIGH donor BKV serostatus was 73%. Five prospectively screened patients (14%) developed early BKV viremia, and an additional 4 (11%) had late onset of BKV viremia. There were three cases (8%) of BKVAN. LOW BKV serostatus was significantly associated with early BKV viremia (p = 0.02). Donor HIGH to recipient LOW (HIGH/LOW) had the highest risk of BKV viremia (4/7; 57%), compared with LOW/LOW (0/3; 0%) and recipient HIGH (1/26; 4%) (p = 0.004). BKV IgG titers are low in young pediatric kidney transplant recipients, and LOW BKV serostatus is associated with an increased risk of early BKV infection post-transplant, particularly in the context of donor with HIGH BKV serostatus.