JC Polyomavirus-Associated Nephropathy Case Report: Clinical and Laboratory Learning.

Introduction: John Cunningham (JC) virus is commonly associated with progressive multifocal leukoencephalopathy. However, this polyomavirus can also be a rare etiological agent of nephropathy in renal transplant recipients. Polyomavirus-associated nephropathy (PVAN) can be difficult to treat, resulting in graft dysfunction and failure. Details: We report a rare case of JC-PVAN in a deceased donor kidney transplant recipient. Following a decline in renal function approximately 4 years post-transplant, the patient underwent biopsy and SV40 staining. A diagnosis of early/mild PVAN was made. Confirmatory PCR testing for BK virus, the virus most commonly associated with PVAN, was repeatedly negative. PCR for JC virus, a much rarer cause of nephropathy, was not performed as testing was not within our laboratory testing scope. Approximately 6 years post-transplant, following further pathological examination and exclusion of BK virus, JC virus was confirmed as the cause of graft dysfunction via off-scope PCR testing. Reductions in immunosuppression were implemented following the initial PVAN diagnosis, however, decline in renal function continued. The patient returned to haemodialysis 8 years post-transplant. Discussion: This paper highlights the challenges faced achieving the diagnosis of JC virus and importance of collaboration between clinical and laboratory teams to ensure appropriate testing to aid diagnosis. In addition, we aim to increase the inclusion of JC virus in the differential diagnosis in cases of nephropathy in allograft recipients with unclear aetiology.