Specimen Required

Human serum and plasma (EDTA, heparin or sodium citrate).

Specimen Minimum Volume

0.4 mL

Transport Temperature

*The samples should be stored for not more than 14 days at 2-8^°C.

**For longer delay, freeze at -10^°C or colder.

Reject Due To

Useful For

Determining whether a patient (especially organ donors, blood donors, and prospective transplant recipients) had CMV infection in the past.

Clinical Information

Cytomegalovirus (CMV) is a significant cause of morbidity and mortality, especially in organ transplant recipients and individuals with AIDS. CMV is also responsible for congenital disease of the newborn. The most common infections with CMV in immunocompromised hosts result from reactivation of the virus (latent) from a previous infection, transmission of the virus from a donor organ or blood product, or initial or primary contact with the virus in a seronegative patient. Infection in immunologically normal patients can cause mononucleosis similar to that produced by infection with Epstein-Barr virus.

Infections with cytomegalovirus (CMV), a member of the herpesvirus family, are common in humans and are usually mild and asymptomatic; however, infection in pregnant women, newborns, and immunocompromised individuals may pose a significant medical risk. In utero infection may result in sequelae of varying degree including mental retardation, choriorentinitis, hearing loss and neurologic problems. An individual may undergo primary infection with CMV, reinfection with exogenous virus or reactivation of latent virus.

The presence of CMV specific IgG antibody does not assure protection from disease. The renal transplant patient with primary infection develops significantly more viremia and symptomatic diseases than does the patient with recurrent infection. The provision of seronegative blood products to selected patients remains a vital consideration in patient management. Serologic tests can be used to identify seronegative individuals and seronegative donors of organs or blood products.

CMV acquisition in infants can occur transplacentally following maternal infection, during birth by contact with the virus excreted from the cervix or following birth through the ingestion of infected maternal breast milk. Both seronegative individuals and infants may acquire CMV through infected blood products or contact with an infected individual. Children beyond the neonatal period are susceptible to infection and subsequent transmission of CMV when in day care. CMV has been isolated from contaminated environmental surfaces; however, the role of fomites in CMV transmission has not been established.

Reference Values

Anti-CMV IgG: NONREACTIVE

Interpretation

A NONREACTIVE CMV IgG result indicates no prior exposure to CMV and, therefore susceptibility to primary infection.

A REACTIVE CMV IgG result indicates past or current CMV infection. Such individuals are potentially at risk of transmitting CMV infection through blood products; the likelihood of transmission by other modes is not known.

A history of seroconversion from NEGATIVE to POSITIVE IgG is diagnostic of primary infection and may be beneficial in evaluating a pregnant woman with symptoms of viral disease.

Clinical Reference

Crumpacker II, C. S., and Zhang, J. L. 2010. Cytomegalovirus, p. 1971-1987. In Mandell, D., Bennett, J. E., and Dolin, R. Principles and practice of infectious diseases, 7^th ed., vol. 2. Churchill Livingstone, Elsevier, Philadelphia, PA.

Hodinka, R. L. 2007. Human Cytomegalovirus, p. 1549-1563. In Murray, P. R., Baron, E. J., Jorgensen, J. H., Landry, M. L., and Pfaller, M. A. Manual of Clinical Microbiology, 9^th ed., vol. 2. ASM Press, American Society for Microbiology, Washington, DC.

Abbott. 2007. Architect System CMV IgM Package insert. Abbott Ireland, Diagnostics Division, Sligo, Ireland.

Abbott. 2008. Architect System CMV IgG Package insert. Abbott Ireland, Diagnostics Division, Sligo, Ireland.

Method Description

The ARCHITECT CMV IgG assay is a two-step immunoassay for the qualitative detection of IgM and IgG antibodies in human serum and plasma. In the first step, sample, assay diluent, and coated paramagnetic microparticles are combined. Anti-CMV IgG present in the sample binds to the CMV virus lysate (strain AD169) and recombinant CMV antigen coated microparticles. After washing, anti-human IgG acridinium-labeled conjugate is added to create a reaction mixture. Following another wash cycle, pretrigger and trigger solutions are added to the reaction mixture. The resulting chemiluminescent reaction is measured as relative light units (RLUs). The presence or absence of anti-CMV IgG in the sample is determined by comparing the chemiluminescent signal in the reaction to the cutoff signal determined from a previous calibration. If the chemiluminescent signal in the specimen is greater than or equal to the cutoff signal, the sample is considered reactive for anti-CMV IgG.

Performing Laboratory Location

Newfoundland & Labrador Public Health Laboratory

St. John’s