A regulatory region rearranged BK virus is associated with tubulointerstitial nephritis in a rejected renal allograft

A renal allograft transplant patient with high serum creatinine presented c linical symptoms of rejection. Sections of renal biopsy tissue showed monon uclear leukocyte infiltration in the tubulointerstitium and nuclear enlarge ment with inclusions in the tubular epithelium. The morphological character istics resembled polyomavirus-induced interstitial nephritis. Electron micr oscopy of the nuclear inclusions showed paracrystalline line arrays of nake d viral particles with a diameter of 45 nm. Molecular studies revealed that a new variant of BK virus (BKV) with rearrangement at the regulatory regio n was involved in the nephritis. The BKV regulatory region contained a tand em repeat from the P-block to the Q-block causing duplication of several im portant transcriptional elements or transcriptional factor binding motifs. This is the first report to show a naturally occurring BKV variant with reg ulatory region rearrangement associated with tubulointerstitial nephritis. J. Med. Virol. 64: 82-88, 2001. (C) 2001 Wiley-Liss, Inc.