Evaluation of the COBAS AMPLICOR CMV MONITOR test for detection of viral DNA in specimens taken from patients after liver transplantation

Detection of cytomegalovirus (CMV) DNA in blood by PCR is a sensitive metho d for the detection of infection in patients posttransplantation. The test, however, has low specificity for the identification of overt CMV disease. Quantitative CMV PCR has been shown to overcome this shortcoming. The COBAS AMPLICOR CMV MONITOR test was evaluated by using consecutive serum and per ipheral blood mononuclear cell (PBMN) samples from liver transplant patient s. Twenty-five patients had CMV viremia (by shell vial cell culture assay) and/or tissue-invasive disease (by biopsy); 20 had no active infection. A t otal of 262 serum and 62 PBMN specimens were tested. Of 159 serum specimens from patients with overt CMV infection, the COBAS assay detected CMV DNA i n 21 patients (sensitivity; 84%). Only 1 of 103 samples from patients with no evidence of active infection had detectable CMV DNA (341 copies/ml). By comparison of 62 matching serum and PBMN samples by the same assay, 12 PBMN samples were exclusively positive, whereas only 2 serum samples were exclu sively positive (P < 0.05). At the time of clinical CMV infection, viral co py numbers were higher in PBMNs than serum from four of five patients. The COBAS AMPLICOR CMV MONITOR test is a sensitive and specific test for the qu antitative detection of CMV DNA in blood. Clinical applications of the assa y will require further validation with samples from a larger population of transplant patients.