The long persistence of CMV DNA in the blood of renal transplant patients after recovery from CMV infection

A total of 30-50% of all renal transplant recipients undergo infections caused by human cytomegalovirus. With the introduction of ganciclovir and foscarnet for specific antiviral therapy there is an increasing demand for diagnostic tools that allow the early and rapid identification of CMV as the causative agent of the observed disease. We and others previously showed the direct detection of pp65 antigen in peripheral blood leukocytes to be an excellent marker for active cytomegalovirus infection. In order to establish whether the detection of CMV DNA by the polymerase chain reaction (PCR) supplies further information in this regard, we compared both methods. In 41 renal transplant patients the PCR assay yielded a sensitivity of 100% compared with 87.5% of the antigenemia assay. Specificities reached 67% and 92.5%, respectively. In 5 patients without both serological signs of infection and antigenemia, CMV DNA was also found. The duration of CMV DNA detection in PBL during active infection was significantly longer than antigenemia. Even after successful treatment of symptomatic CMV disease, DNA was present for a period of weeks without any relapse of disease. In contrast, antigenemia disappeared after antiviral therapy and reappeared only in one patient with relapse of CMV disease. We conclude that PCR offers no advantages over antigen detection in monitoring for CMV infections after renal transplantation.