Evaluation of CMV viral load using TaqMan??? CMV quantitative PCR and comparison with CMV Antigenemia in heart and lung transplant recipients

Abstract

Quantitative assessment of cytomegalovirus (CMV) infection using the antigenemia test has been used to monitor CMV infection in heart and lung transplant patients enabling a preemptive treatment strategy. However, the method is labour intensive, samples have to be processed within a few hours and requires skilled interpretation. A comparative prospective evaluation of a real-time TaqMan™ CMV quantitative PCR (QPCR) with the CMV antigenemia was undertaken. A real-time quantitative TaqMan™ CMV PCR from EDTA bloods was developed. In this study 25 heart transplant and single-lung transplant patients were monitored posttransplantation by antigenemia and TaqMan™ CMV QPCR. CMV DNA extracted from EDTA blood was amplified by TaqMan™ QPCR using primers and probe designed from the CMV glycoprotein B (gB) gene. Quantification of the genome copies is extrapolated from a standard curve generated from amplification of quantified standards. Antigenaemia levels and TaqMan™ CMV QPCR genome copies showed a linear correlation between the two assays (R=0.843, P =0.001). A clinically significant threshold of 50 CMV pp65 antigen positive polymorphonuclear leucocytes (PMNLs) per 200 000 cells previously reported was used to extrapolate an equivalent value of 40 000 (log 4.6) genome copies per ml of blood for the TaqMan™ CMV QPCR. The TaqMan™ system enables a rapid high-throughput of samples. The TaqMan™ CMV QPCR can be used as an accurate and robust alternative to the antigenemia test to predict CMV disease and to monitor effectiveness of treatment.