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

Background: 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.

Methods: 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.

Results: 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).

Conclusion: 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.