Quantitative analysis of cytomegalovirus load using a real-time PCR assay

A novel real-time PCR assay system was developed to quantify the cytomegalo virus (CMV) genome load. The real-time PCR assay could detect from 6 to ove r 10(6) copies of CMV-DNA with a wide linear range. The virus load of immun ocompromised patients with symptomatic CMV infections was quantified and co mpared to that of asymptomatic ones. In symptomatic patients, all 17 periph eral blood leukocytes were positive for CMV DNA, and its mean value was 10( 3.3) copies/10(6) cells. On the other hand, only 9 of 38 samples (24%) were positive in the asymptomatic patients, and its mean titer was lower (10(2. 0) copies/10(6) cells) than that of the symptomatic group (P = 0.002). In p lasma, the virus genome was detected in 13 out of 17 samples from symptomat ic patients (76%), and its mean value was 10(4.0) copies/ml. In contrast, f or the asymptomatic group, only one out of 36 samples were positive (3%). F inally, this system was used to monitor two patients with CMV infections se rially. The CMV DNA copy number changed with their clinical symptoms and an ti-CMV therapy, and virtually paralleled the result of the pp65 antigenemia assay in both cases. In one patient with the cord blood transplantation, h owever, the CMV DNA became positive faster than the antigenemia assay. Thes e results indicate that this assay is sensitive and useful for estimating t he CMV genome load not only in peripheral blood leukocytes but also in plas ma. It can be very helpful for diagnosing CMV-related diseases and monitori ng the virus load in patients with CMV infections. J. Med. Virol. 60:455-46 2, 2000. (C) 2000 Wiley-Liss, Inc.