Sensitive detection of cytomegalovirus infection in transplant recipients using nucleic acid sequence-based amplification

THE MAJORITY of the adult human population is seropositive for cytomegalovirus (CMV), a member of the b-herpesvirus family. Normally, infection of immunocompetent individuals does not cause disease. In contrast, infection of immunocompromised individuals, such as patients with AIDS and transplant recipients, can cause severe complications and can even lead to death. Therefore, early detection of active CMV infection is necessary to start effective antiviral treatment. Nucleic Acid Sequence-Based Amplification (NASBA) has been developed for the specific amplification of RNA. In previous studies, we evaluated the diagnostic value of monitoring the expression of the CMV immediate early (IE) 1 and late pp67 mRNA using NASBA, in peripheral blood cells of kidney transplant (Tx) patients. The IE 1 mRNA is expressed directly after entrance of the virus into a cell, while pp67 mRNA is expressed in a late stage in the replication cycle. NASBA results were compared to the techniques that are routinely being used for the detection of CMV: pp65-antigenemia, virus culture, and serology. From this study it was concluded that IE NASBA is a very sensitive assay that detects the onset of CMV infection significantly earlier than the other assays. This is especially valuable for patients that are at risk for symptomatic CMV infection, i.e., seronegative patients with an organ of a seropositive donor and/or intense immunesuppression. The sensitivity and specificity values of pp67 NASBA were comparable to those of the antigenemia assay. We set up a similar study to evaluate the diagnostic value of IE and pp67 NASBA for liver Tx patients. The liver Tx patients are usually severely ill, immunesuppression is more intense compared to the kidney Tx patients and they often have anti-rejection therapy. The results for IE NASBA are presented in this report. The evaluation of pp67 NASBA is still in progress.