Real-time polymerase chain reaction and laser capture microdissection for the diagnosis of BK virus infection in renal allografts.

We used real-time polymerase chain reaction (PCR) technology to detect BK virus (BKV) in H and E-stained kidney biopsy sections, using laser capture microdissection. Renal allograft biopsy specimens from 4 patients with the histopathologic diagnosis of BKV-associated nephropathy (BKVAN; group 1) and 3 patients suspected to have BKVAN but without diagnostic histologic features (group 2) were retrieved. Diagnostic inclusion-bearing cells were microdissected by laser capture microscopy from group 1. Renal tubular epithelial cells were microdissected randomly in group 2. DNA was extracted and real-time amplification performed using primers targeting the large "T" and small "t" regions of the BKV and JC virus genomes. Tubular epithelial cells from a case without evidence of BKV infection were used as negative controls in a similar reaction. BKV presence was demonstrated only in epithelial cells containing typical viral inclusions. Group 2 and negative control samples were confirmed as negative for BKVAN. Real-time PCR technology can be used to detect BKV in H and E-stained, paraffin-embedded tissue sections. This technique detected BKV in tubular epithelial cells of renal allografts. To our knowledge, this is the first report of detecting BKV in laser capture microdissected renal biopsy specimens using real-time PCR.