Assessing immunity to rubella virus: A plea for standardization of igg (immuno)assays

Elise Bouthry, Milena Furione, Daniela Huzly, Adaeze Ogee-Nwankwo, Lijuan Hao, Adebola Adebayo, Joseph Icenogle, Antonella Sarasini, Maria Grazia Revello, Liliane Grangeot-Keros, Christelle Vauloup-Fellous

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Abstract

Immunity to rubella virus (RV) is commonly determined by measuring specific immunoglobulin G (RV IgG). However, RV IgG results and their interpretation may vary, depending on the immunoassay, even though most commercial immunoassays (CIAs) have been calibrated against an international standard and results are reported in international units per milliliter. A panel of 322 sera collected from pregnant women that tested negative or equivocal for RV IgG in a prior test (routine screening) was selected. This panel was tested with two reference tests, immunoblotting (IB) and neutralization (Nt), and with 8 CIAs widely used in Europe. IB and Nt gave concordant results on 267/322 (82.9%) sera. Of these, 85 (26.4%) sera were negative and 182 (56.5%) sera were positive for both tests. All 85 IB/Nt-negative samples were classified as negative with all CIAs. Of the 182 IB/Nt-positive samples, 25.3 to 61.5% were classified as equivocal and 6 to 64.8% were classified as positive with the CIAs. Wide variations in titers in international units per milliliter were observed. In our series, more than half of the women considered susceptible to RV based on CIA results tested positive for RV antibodies by IB/Nt. Our data suggest that (i) sensitivity of CIAs could be increased by considering equivocal results as positive and (ii) the definition of immunity to RV as the 10-IU/ml usual cutoff as well as the use of quantitative results for clinical decisions may warrant reconsideration. A better standardization of CIAs for RV IgG determination is needed.

Original languageEnglish
Pages (from-to)1720-1725
Number of pages6
JournalJournal of Clinical Microbiology
Volume54
Issue number7
DOIs
Publication statusPublished - Jul 1 2016

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ASJC Scopus subject areas

  • Microbiology (medical)

Cite this

Bouthry, E., Furione, M., Huzly, D., Ogee-Nwankwo, A., Hao, L., Adebayo, A., Icenogle, J., Sarasini, A., Grazia Revello, M., Grangeot-Keros, L., & Vauloup-Fellous, C. (2016). Assessing immunity to rubella virus: A plea for standardization of igg (immuno)assays. Journal of Clinical Microbiology, 54(7), 1720-1725. https://doi.org/10.1128/JCM.00800-16