biostudies-literatureUnknown14(1)Ortega CRubella virus (RV) IgG quantification is essential for verifying immunity, particularly in prenatal care. However, substantial variability exists among commercial immunoassays, especially when testing low-antibody sera. In this study, we evaluated five commercial assays-four chemiluminescent immunoassays (CLIAs) and one Enzyme-linked Immunosorbent Assay (ELISA)-using a recombinant immunoblot (IB) as the reference method. A panel of 137 serum samples with low or undetectable IgG levels was analyzed. Sensitivity ranged from 19.6% to 70.1%, while specificity exceeded 94%. Only 18.6% of immunoblot-positive samples tested positive across all assays. Marked quantitative differences were observed, with the Atellica assay yielding the highest titers and Alinity the lowest. Reclassifying equivocal Microorganisms58https://www.ebi.ac.uk/biostudies/studies/S-EPMC12844522biostudies-literatureEvaluation of Commercial Immunoassays for Rubella Virus IgG Detection in Low-Antibody Sera Using a Recombinant Immunoblot as a Reference Method.PMC12844522Reguera JARodriguez-Granger JCobo FAbreu AOrtega CSampedro-Padilla ASampedro ASerrano JGutierrez-Bautista JFMazuelas PfalseEvaluation of Commercial Immunoassays for Rubella Virus IgG Detection in Low-Antibody Sera Using a Recombinant Immunoblot as a Reference Method.Rubella virus (RV) IgG quantification is essential for verifying immunity, particularly in prenatal care. However, substantial variability exists among commercial immunoassays, especially when testing low-antibody sera. In this study, we evaluated five commercial assays-four chemiluminescent immunoassays (CLIAs) and one Enzyme-linked Immunosorbent Assay (ELISA)-using a recombinant immunoblot (IB) as the reference method. A panel of 137 serum samples with low or undetectable IgG levels was analyzed. Sensitivity ranged from 19.6% to 70.1%, while specificity exceeded 94%. Only 18.6% of immunoblot-positive samples tested positive across all assays. Marked quantitative differences were observed, with the Atellica assay yielding the highest titers and Alinity the lowest. Reclassifying equivocal 2025-01-01T00:00:00Z2025 Dec2026-06-15T03:19:59.108Z2026-06-15T03:11:21.521ZS-EPMC128445224159757810.3390/microorganisms14010058