This study used real-time polymerase chain reaction (PCR) for quantification of BKV DNA in the plasma of kidney transplant donors (n = 38) and recipients (n = 87) at the time of surgery. The control BKV DNA was manufactured from a known positive human sample, by cloning a 133-bp PCR product of bases 4,329 to 4,462 of the large T-antigen (TAg) of BKV in a plasmid vector.
Twenty-five of 87 recipient (28.7%) and 17/38 donor (44.7%) plasma samples were positive for BKV DNA at the time of transplantation with a median viral load of 910 (range 49-4770) and 312 (range 79-1508) copies per mL plasma, respectively. Six of 38 donor-recipient pairs showed viremia in both the recipient and donor: 1 developed histologically proven BKN at 18 months, 1 showed positive immunohistochemistry for SV40 TAg, and 2 others had high levels of viremia (14,545 copies at 6 and 2,617,524 copies at 3 months). None of the other 81 recipients showed evidence of BKN in the follow-up period.
This study showed that 28%of recipients and 44%of donors displayed baseline positivity for BKV DNA in plasma, which is higher than the reported incidence in the West. The baseline levels of BKV DNA in recipients with end-stage renal disease were higher than in donors. Dual positivity for BKV DNA in the plasma of donor-recipient pairs conferred a high risk of development of BK nephropathy in the allografted kidney.