Avidity of IgG antibodies distinguishes primary from non-primary cytomegalovirus infection in pregnant women.

Abstract

BACKGROUND:

Human cytomegalovirus (HCMV) is the most common cause of viral intrauterine infection. Fetal damage is mostly linked to maternal primary infection. It is therefore important to differentiate primary from non-primary infection in pregnant females. IgM tests often used for this purpose are not reliable enough.

OBJECTIVE:

To evaluate an HCMV-IgG urea-elution assay for its ability to distinguish primary from non-primary infection. In this assay, soaking the antigen-antibody complex with an urea containing solution frees antibodies with low avidity but has no influence on those with high avidity. An avidity index (AI) was calculated: AI = (OD with urea/OD without urea) x 100.

STUDY DESIGN:

HCMV-IgG avidity was measured on a single serum of 79 patients with past infection (pregnant women, graft recipients and blood donors) and of 63 patients (78 sera) with documented seroconversion (pregnant women and graft recipients). Sixty-one pregnant women positive or equivocal for HCMV-IgM but without a documented seroconversion were included in this study.

RESULTS:

Most (72/79) of the patients with past infection had an AI > 65% and all but one had an AI > 50%. In pregnant women, in the case of a primary infection within the past 3 months, AI are usually (51/53) < 50% and never > 65%. Among the IgM positive pregnant women who lack a seroconversion history, 38 had AI > 65% suggestive of an infection that had occurred at least 3 months earlier, 11 had an AI in a grey area between 50 and 65% and 12 had an AI < 50%, suggestive of a recent primary infection.

CONCLUSIONS:

In pregnant women, measurement of the IgG avidity may help to date a HCMV infection, an AI > 65% highly suggests a past infection while an AI < 50% corresponds to a recent primary infection.

• Authors: M Bodéus, S Feyder, P Goubau
• Journal: Clinical and diagnostic virology (Clin Diagn Virol) Vol. 9 Issue 1 Pg. 9-16 (Jan 1998) ISSN: 0928-0197 [Print] Netherlands
• PMID: 9562853 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Immunoglobulin G

Topics

• Antibody Affinity (immunology)
• Cytomegalovirus Infections (immunology, virology)
• Female
• Humans
• Immunoenzyme Techniques
• Immunoglobulin G (analysis, immunology)
• Pregnancy
• Pregnancy Complications, Infectious (immunology, virology)