Background: BK nephropathy (BKN) is an important complication of renal transplantation, with a reported incidence between 1% and 10% in different parts of the world. Known risk factors for the development of BKN are the recently introduced immunosuppressants and steroids. However, the preexisting viral load may add to the risk for development of BKN. Therefore, the present study was designed to monitor the baseline BK virus (BKV) DNA in renal transplant donors and recipients in India for correlation with the development of BKN.
Methods: 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.
Results: 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.
Conclusions: 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.
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