Determination of cytomegalovirus IgG antibodies using stable element labeling and inductively coupled plasma mass spectrometry: Further evidence of the feasibility of antibody detection.

Cytomegalovirus (CMV), a β-herpesvirus with broad infectivity, establishes lifelong latency and poses significant risks to immunocompromised individuals, pregnant women, and newborns. Current diagnostic assays detecting serum immunoglobulin G (IgG) are mainly qualitative or semi-quantitative, limiting accurate quantification of high antibody levels. Inductively coupled plasma-mass spectrometry (ICP-MS), based on stable lanthanide rare-earth element labeling, offers high sensitivity, absence of signal interference, and a broad detection range, making it suitable for biomarker detection. This study proposes a technique that combines element-labeled immunoassay and ICP-MS, providing a novel integration for quantitatively detecting CMV IgG. The system was established based on the indirect method. Recombinant CMV antigens were immobilized on magnetic beads and interacted with target antibodies in serum. Following washing, Tb-labeled anti-human IgG antibodies were introduced to complete the immune complex. Quantitative analysis was performed by detecting the Tb signal through ICP-MS. Method validation and evaluation of diagnostic performance in clinical samples followed relevant regulatory and clinical laboratory standards. The test showed excellent linearity, with a maximum quantification limit of 900 U/mL. The coefficients of variation (CV) for low- and high-concentration samples were 4.1% and 5.5%. Interference and day-to-day variations were below 10%. Recoveries ranged from 90.62% to 102.74%. Receiver operating characteristic curve area versus Roche electrochemiluminescence immunoassay (ECLIA) was 0.908, indicating strong diagnostic performance. In summary, we have successfully established a quantitative detection system for CMV IgG antibodies based on stable element labeling and ICP-MS, which meets the requirements for clinical laboratory testing and represents a novel application of mass spectrometry in clinical practice.