Evaluation of new-onset BK viruria in post-renal transplant recipients by quantitative PCR

The BK polyomavirus infection poses a substantial challenge for organ transplant recipients due to immunosuppression, resulting in BK virus-associated nephropathy (BKVAN) and a considerable risk of graft loss. Screening and prompt decrease of immunosuppression are essential for averting these consequences. We examined the frequency of BK viruria (viral load in urine) among post-renal transplant recipients, along with its association with age, viral load, and the timing of viral reactivation.

The prospective cohort study was conducted at the Tertiary Care Hospital in Rawalpindi over a 12-month period, from January 1 to December 31, 2023. Urine specimens from 108 renal transplant recipients were collected and analysed for BK viruria every three months during the follow-up assessments. DNA extraction was performed using TANbead extractor, and amplification was carried out with Bio-Rad CFX-96 thermal cycler using Sacace TM amplification kit. Data was analysed using SPSS version 27.

In the cohort of 108 renal transplant recipients, BK viruria was detected in 16.7 % of cases. There was a higher prevalence of BK viruria in females (20 %) than males (16 %). The majority of positive cases were within the 41-60 years age group (61.1 %). Most of the patients (66.6 %) had viral loads below 1 million copies/ml. BK viruria was predominantly detected during the third quarter (between 7 and 9 months) post-transplant. The Chi-square test was applied between age and viral load, showing a significant association (p = 0.01). Similarly, gender and viral load also showed a significant relationship (p = 0.019).

The study showed the frequency of 16.7 % of BK viruria in our small cohort after renal transplantation during the initial 12 months post-transplant. Age of recipients correlated with viral load and time of viral reactivation: middle-aged recipients had higher viral loads. BK viruria increased progressively over the initial nine months, with peak incidence in the third quarter post-transplant.