Human cytomegalovirus (HCMV or CMV) is a human viral pathogen belonging to the Herpesvirus family found in both the developed industrial societies and in isolated aboriginal groups. It can be transmitted through blood, oropharyngeal secretions, urine, cervical and vaginal excretions, spermatic fluids, breast milk, tears and feces. Primary infections with CMV in immunocompetent individuals are usually asymptomatic and often give rise to undetected latent infections. Peripheral blood mononuclear cells and endothelial cells appear to be the major sites of infection. CMV remains in a latent stage in monocytes/macrophages in humans. Latently infected individuals may intermittently shed the virus in their body fluids and thus infect others. Immunocompromised individuals, including neonates, transplant patients and AIDS patients, are at high risk for developing severe CMV infections that can lead to a higher rate of morbidity and mortality. Severe clinical manifestations of CMV disease include CMV syndrome, retinitis, gastroenteritis, hepatitis, encephalitis, esophagitis, enterocolitis, pancreatitis and pneumonia. The risk of CMV disease is clearly defined by high viral load, which underscores the important role of viral titer in disease pathogenesis. Studies in transplant recipients and AIDS patients have shown that PCR detection of CMV DNA is highly predictive of subsequent development and clinical outcome of disease. Quantitative assessments of CMV DNA levels have shown that high viral loads, as well as increases of viral load over time, are correlated with worse clinical prognoses for a number of CMV risk states. Furthermore, quantitative PCR assays allow for monitoring of antiviral treatment efficacy and indirect evaluation of viral resistance. The use of CMV viral load is recommended in current treatment guidelines in solid organ transplant to monitor patients for the risk of CMV disease development and the need for preemptive treatment, and for monitoring patients with active CMV disease for treatment response. It is also recommended as part of the diagnostic criteria for identifying CMV disease in hematopoietic stem cell transplant recipients.
The quantification range of this assay is 150 to 4,000,000 copies/mL (2.18 log to 6.60 log copies/mL).
A result of "Not detected" indicates the absence of cytomegalovirus (CMV) DNA in the plasma.
A result of "<150 copies/mL (<2.18 log copies/mL)" indicates that CMV DNA is detected in the plasma, but the assay cannot accurately quantify the CMV DNA present below this level. A quantitative value (reported in copies/mL and log copies/mL) indicates the level of CMV DNA (ie, viral load) present in the plasma.
A result of ">4,000,000 copies/mL (>6.60 log copies/mL)" indicates that CMV DNA level present in plasma is above 4,000,000 copies/mL (6.60 log copies/mL), and the assay cannot accurately quantify CMV DNA present above this level.
Manufacturer’s package insert, COBAS® AmpliPrep/COBAS® TaqMan®CMV Test, September 2019, Roche Molecular Systems, NJ 08876 Branchburg, USA.