Evaluation of polyomavirus BK cellular immune response by an ELISpot assay and relation to viral replication in kidney transplant recipients.

The failure of immune surveillance may be associated with polyomavirus BK reactivation, potentially leading to the development of nephropathy in kidney transplantation. BK-specific cellular immune response may be used to modulate immunosuppressive therapy, but few studies have investigated the topic. Herein, we serially evaluated BK-specific response in 149 kidney transplant recipients and found that only 14/149 (9.4%) were responders. Episodes of viral reactivation (viremia and/or viruria) occurred only in non-responder patients. The frequency of BK-specific immune response appears to be lower than that for other persistently infecting viruses such as cytomegalovirus.

Double-step PCR assay to quantify Epstein-Barr viral load in peripheral blood.

Posttransplant lymphoproliferative disorders (PTLD) are a severe complication arising in solid organ transplant patients. A strong correlation between Epstein-Barr virus (EBV) infection, the grade and type of immunosuppression, and the development of PTLD has been recognized. This article describes the development of a double-step polymerase chain reaction (PCR) assay for the quantification of EBV-deoxyribonucleic acid (DNA) to monitor EBV infection. Screening of samples containing >/=10(3) viral genomes/10(5) peripheral blood mononuclear cells (PBMC) or 100 micro L serum by a semiquantitative PCR assay is followed by quantification of the samples containing a high number of viral genomes in a quantitative-competitive (QC)-PCR assay. Screening by semiquantitative PCR selects samples with a high number of viral genomes for use in the more labor-intensive and expensive QC-PCR assay and thus provides a handy means for quantitative DNA analysis of large numbers of samples. Our double-step PCR assay can be employed in EBV viral load measurement in PBMC and serum samples to monitor transplanted patients at risk to develop PTLD.