What is the role of antigen testing in the workup of cytomegalovirus (CMV) infection?

Updated: Jul 07, 2021
  • Author: Ricardo Cedeno-Mendoza, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Antigenemia is defined as the detection of the CMV pp65 antigen in leukocytes. [8]

The pp65 assay is used to detect messenger matrix proteins on the CMV virus, with either immunofluorescence assay or messenger RNA amplification. These proteins are typically expressed only during viral replication.

Antigen tests are often the basis for institution of antiviral therapy in transplant recipients and may allow for the detection of subclinical disease in high-risk patients. The assay is sensitive and specific yields results quickly.

Antigen assays cannot be used in patients with leukopenia, as these tests detect antigen within neutrophils.

In immunocompromised patients, low or moderate CMV antigenemia may indicate reactivation or infection. [9]

It has been reported that the pp65 antigen assay and quantitative CMV PCR (COBAS Amplicor Monitor Test; see Quantitative polymerase chain reaction) yield similar effectiveness in diagnosing and monitoring patients with active CMV infection. [49]

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