Prospective monitoring of BK virus reactivation in renal transplant recipients in North India

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 BKvirus (BKV) in renal transplant recipients in India. Patients and methods. In this study, 32 renal allograft recipients were prospectively monitoredwith protocol biopsies of allografts, BKV DNA load in plasma, and viral particles in urine by electron microscopy (EM) on day1, 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 les by EM at day 1, 1 month, 3 months, and 6 months, respectively. BKV DNApositivity in plasmawas 25.8%, 42.9%, 15.4%, and 20% at day1, 1month, 3 months, and 6 months, respectively, with mean BKVcopy number/mL plasma of 1796, 1029, 2611, and 3318, respectively. Atotal 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 eff ects of BKN, although 8% biopsieswere SV-40 large T antigen (SV-40 TAg) 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 boolean AND 3 months post transplantation. The baseline viremia in donors was predictive of viremia positivity in the posttransplantation 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 BKVat any time during a 6 -month follow-up. The highest incidence of BKviruria and viremia occurred at 1month. In protocol biopsies, focal positivity of SV-40 TAg was seen in 8% biopsies.