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. Early diagnosis is important to plan early therapeutic strategies. The epidemiology and evolution of BKN is relatively unknown in India and hence, the present study has been designed to prospectively monitor the activation of BK virus (BKV) in renal transplant recipients in India.
Patients and methods: In this study, 32 renal allograft recipients were prospectively monitored with protocol biopsies of allografts, BKV DNA load in plasma, and viral particles in urine by electron microscopy (EM) on day 1, and at 1, 3, and 6 months. Additionally, the baseline BKV DNA load in plasma was quantitated in 21 corresponding donors.
Results: On follow-up in 32 recipients, 9.7%, 23.8%, 19.2%, and 13.3% of patients showed viral profiles by EM at day 1, 1 month, 3 months, and 6 months, respectively. BKV DNA positivity in plasma was 25.8%, 42.9%, 15.4%, and 20% at day 1, 1 month, 3 months, and 6 months, respectively, with mean BKV copy number/mL plasma of 1796, 1029, 2611, and 3318, respectively. A total of 15.7% (17/108) urine samples of 32 renal recipients were positive by urine EM. Out of 100 protocol biopsies, none developed histologically demonstrable cytopathic effects of BKN, although 8% biopsies were SV-40 large T antigen (SV-40 T Ag) positive. By quantitative real-time polymerase chain reaction assay, 27/108 (25%) of recipients' plasma samples were positive for BKV. Peak viremia and viruria occurred at 1-3 months post transplantation. The baseline viremia in donors was predictive of viremia positivity in the post-transplantation period at 1 month. Twenty-four episodes of graft dysfunction were attributed mainly to rejection.
Conclusion: The study shows a total of 15.7% and 25% urine and plasma samples were positive for BKV at any time during a 6-month follow-up. The highest incidence of BK viruria and viremia occurred at 1 month. In protocol biopsies, focal positivity of SV-40 T Ag was seen in 8% biopsies.
© 2011 John Wiley & Sons A/S.