Quantitative Viral Load Monitoring and Cidofovir Therapy in BK Virus Nephropathy

Abstract

Background: BK virus nephropathy (BKVN) has been increasingly recognized as an important cause of renal transplant dysfunction, but no specific antiviral therapy is currently available. Furthermore, a method evaluating the degree of viral infection has not been developed yet. Recently, there have been several case reports in which BKVN was successfully treated with cidofovir injection. In the current study, we report a case with BKVN successfully treated with cidofovir injection. In addition, we assessed the usefulness of quantitative viral load monitoring using a competitive polymerase chain reaction (PCR) in the treatment of BKVN.

Methods: A renal allograft recipient with BKVN was injected with cidofovir. To monitor BK viral load in urine and plasma, we developed a competitive PCR assay and followed the patient prospectively.

Results: A 49 year old renal transplant recipient developed a progressive rise in serum creatinine reaching 1.9 mg/dL at 15 months post-transplantation. Subsequently, the patient was diagnosed as BKVAN by allograft biopsy. At this time, BKV DNA was detected in plasma and urine. Despite a reduction of the dose of mycophenolate mofetil, serum creatinine continued to rise, which prompted the initiation of cidofovir trial. The patient was given intravenous cidofovir. After cidofovir treatment, BK virus associated findings disappeared on repeat biopsy, and BK virus in plasma was decreased to the undetectable level. For 7 months after cidofovir treatment, her renal function remained stable.

Conclusion: Cidofovir therapy may be effective in the treatment for BKVN. Viral load in plasma reflected well the clinical and pathological course of the BK virus infection.