- New onset BK Virus Nephropathy (BKVN) diagnosed by a positive plasma polymerase chain reaction (PCR) assay for BK virus deoxyribonucleic acid (DNA) or by a renal biopsy demonstrating BK virus (by immunohistochemistry, electron microscopy and/or in situ hybridization) obtained as part of standard medical care within 60 days prior to receipt of first dose of study drug.