A sandwich chemiluminescent magnetic microparticle immunoassay for cryptococcal antigen detection

ABSTRACT

Background

Cryptococcosis is a global invasive mycosis associated with significant morbidity and mortality. Cryptococcal antigen (CrAg) testing from serum and cerebrospinal fluid (CSF) has been regarded as a gold standard for early diagnosis. This study aimed to develop and validate a rapid and sensitive sandwich chemiluminescent magnetic microparticle immunoassay (CMIA) for quantitative detection of CrAg in sera.

Research design and methods

CMIA is based on magnetic beads modified with capture antibodies and biotinylated antibodies and Streptavidin-polyHRP, where biotinylated antibodies functioned as the recognition element and Streptavidin-polyHRP as the signal component. Assay parameters were first optimized, and then assay performances were evaluated.

Results

Under optimized conditions, the total runtime of the CMIA was 22 min. The assay had a wide linear range (2 –10,000 ng/mL) and high analytical sensitivity (0.24 ng/mL), together with acceptable reproducibility, accuracy, and stability. Besides, it exhibited no cross-reactivity with other pathogens. Importantly, the assay showed 92.91% (95% CI, 80.97–93.02%) overall qualitative agreement with a commercial ELISA kit in a retrospective cohort of 55 cases with confirmed cryptococcal infection, and 72 controls without evidence of invasive fungal disease (IFD).

Conclusion

These results demonstrated that the present study paved a novel strategy for reliable quantitative detection of CrAg in sera.

KEYWORDS:

• Cryptococcosis
• diagnosis
• antigen
• chemiluminescence
• microparticles

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Authorship contributions

J Li: Funding acquisition, Project administration, Formal analysis, Writing – review & editing. Y Guo: Conceptualization, Methodology, Data curation, Writing – original draft. All the authors approved of the version to be published and agreed to be accountable for all aspects of the work.

Ethics approval

This study was approved by the institutional review boards of both centers of Tianjin Medical University General Hospital and Tianjin Chest Hospital (Grant No: 2023YS-019-1) and a waiver of informed consent was granted.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/14737159.2024.2369243

Additional information

Funding

This manuscript was funded by the Tianjin Health Research Project with Grant No. TJWJ2023QN066.