Cytomegalovirus (CMV) DNA amplification from plasma compared with CMV pp65 antigen (ppUL83) detection in leukocytes for early diagnosis of symptomatic CMV infection in kidney transplant patients.

Rapid laboratory methods for the early detection of cytomegalovirus (CMV) are needed for the prevention of CMV disease in transplant recipients. These methods should not only be able to detect the virus but also be highly predictive for CMV disease. The clinical value of a simple and rapid nested plasma polymerase chain reaction (PCR) was evaluated by comparing the results with CMV pp65 antigen detection in leukocytes (CMV antigenemia assay), virus isolation from leukocytes, CMV IgG and IgM antibody response and clinical data. A total of 471 EDTA blood samples were collected from 85 kidney transplant patients during a 3-4 month period after transplantation. CMV DNA was amplified directly from 10 microliters of plasma while 150000 separated leukocytes were stained for CMV pp65 antigen by each of two monoclonal antibodies. A total of one million leukocytes were used for virus isolation. The PCR protocol used in the present study involves a simple alkaline lysis technique for isolating DNA directly from plasma which is easy and rapid to perform. Twenty-eight patients developed symptomatic CMV infection while asymptomatic infection occurred in 29 patients. CMV pp65 antigen detection had a 75% sensitivity and a 57% positive predictive value for CMV disease development, compared with 64% and 79% sensitivity and 49% and 46% positive predictive value for CMV DNA and viremia, respectively. The median time until detection of CMV in patients with symptomatic CMV infection was 26 days after transplantation, compared with 49 days in asymptomatic patients by any of the methods used. Early appearance (within 8 weeks) of CMV pp65 antigen and CMV DNA had high predictive values for symptomatic infection; repeated detection of pp65 antigen and CMV DNA were more common in symptomatic patients. CMV antigenemia assay and plasma PCR can be used for pre-symptomatic diagnosis of CMV infection. Virus isolation and CMV serology in most cases provide a post-symptomatic diagnosis. The best marker for monitoring kidney transplant patients might be the quantitative CMV antigenemia assay.