Public Health and Environmental Laboratories

Harvest Order Choice: 90214

Synonyms: VIDAS CMV IgG (CMVG)

Program: Virology

Unit: Viral Serology

Useful For: the semi-quantitative automated enzyme-linked fluorescent immunoassay (ELFA) intended for use in determination of CMV immunological experience from a single serum sample, or as an aid in the diagnosis of current CMV infection through evaluation of paired sera for a significant increase in CMV-specific IgG.

Method: Enzyme-Linked Fluorescent Immunoassay

Charge: None

Request Form: SRD-1

Container/ Tube: Serum separator tube

Type: Human serum

Volume: 3 ml

Collection Instructions: Venipuncture

Storage: If specimens cannot be tested onn the day of collection, they should be stored at 2-8 C in stoppered tubes for up to five days. If longer storage is required, the sera should be frozen at   -25 ± 6 C (but only once).

Causes for Rejection: plasma specimen, specimens with microbial contamination, grossly, lipemic, hemolyzed or icteric serum.

Interpretation: Tests with a test value below four indicate that the specimen is considered negative.

Reference Interval: Negative

Limitations: Sera collected very early in the acute stage of disease may have IgG levels <4 AU/ml. The VIDAS CMV IgG (CMVG) Assay demonstrates a linear dilution response to concentration. However, no international standard has been established. Positive test results from cord blood should be interpreted with caution. The presence of total or IgG CMV antibodies in cord blood is usually the result of passive transfer from the mother to the fetus. A negative test, however, may be useful in excluding current infection, but the most definitive diagnosis of active CMV infection requires viral culture. The titer of a single specimen should not be used to aid in the diagnosis of recent infection. Paired (acute and convalescent) samples should be collected and tested concurrently to look for seroconversion which may be indicative of primary or recent infection. Positive test results may not be valid in persons who have received blood transfusions or other blood products in the past several months. Increases in antibody level does not exclude the possibility of CMV infection. No cross-reactivity has been observed with the VIDAS CMV IgG (CMVG) Assay. However, rare heterotypic responses of cytomegalovirus antibodies have been reported in conjunction with herpes simplex virus, influenza A virus and Mycoplasma pneumoniae. The virus causing the infection may not always demonstrate the greater rise in antibody level. Frequently, a differential diagnosis can be made on the basis of the fact that antibody to the infecting virus type is absent or at a very low titer in the acute-phase specimen, wheras antibody to the viral heterotype is already present.

Availability: N/A