The CMV quantitative assay uses real-time PCR to quantitate CMV DNA extracted from plasma of CMV-infected individuals. The test quantifies CMV DNA over different ranges depending on the laboratory and assay methodology " for example 50 " 4,200,000 copies/mL. The first WHO International Standard for human cytomegalovirus (HCMV), NIBSC code 09/162, will help with standardization of nucleic acid amplification technique (NAT)-based assays for human CMV. The FDA-approved COBAS ® AmpliPrep/COBAS ® TaqMan ® CMV Test has a range 1.37E+02 " 9.10E+06 IU/mL.
Normal values: Not detected when the result is below the level of detection of the assay.
Use
Management of CMV-infected individuals undergoing antiviral therapy
Individuals at risk of severe CMV infection
Confirmation of the presence CMV infection
Limitations
Caution should be taken when interpreting results obtained by different laboratories or assay methodologies. Use of IU/mL units is intended to make comparison possible. PCR inhibitors in the patient specimen may lead to underestimation of viral quantitation or in rare cases, false-negative results.