JC virus infection in allograft kidneys: analysis by polymerase chain reaction and immunohistochemistry.

Background: Polyoma virus nephropathy after transplantation is believed to be primarily due to the BK virus. We hypothesized that some cases may be associated with the JC polyoma virus (JCV), which is also known to be latent in the kidney.

Methods: We sought polymerase chain reaction evidence of JCV infection in needle biopsy specimens with and without viral nephropathy. Cases positive by polymerase chain reaction were studied by immunohistochemistry for VP-1 antigen expression.

Results: JCV DNA was found in 7 (36.8%) of 19 allograft kidney biopsy specimens with viral nephropathy and 0 (0%) of 19 native or allograft biopsy specimens without viral nephropathy. Immunohistochemistry localized JCV to the nuclei of tubular epithelial cells in one case.

Conclusions: JCV is detectable in a subset of renal allograft kidneys with polyoma virus nephropathy. The tubular epithelium is identified as a site capable of supporting JCV viral capsid protein VP-1 expression, and hence viral replication.