Publication date: May 20, 2026
Mucosal immunity, including antibodies like immunoglobulin A (IgA), function as the body’s first line of defense in the respiratory tract, particularly against viruses. An anti-rS protein IgA enzyme-linked immunosorbent assay (ELISA) was developed using the Omicron XBB. 1.5 subvariant of SARS-CoV-2 and was validated to demonstrate the suitability of the method for testing saliva from SARS-CoV-2 vaccine clinical trials. This assay successfully met acceptance criteria for inter-/intra-assay precision, specificity, selectivity, linearity, lower/upper limits of quantitation, and assay robustness. The IgA in saliva was stable for up to 7 freeze/thaw cycles, for up to 48 h at 24 ^0C, up to 7 days at 4 ^0C, up to 3 weeks at -20 ^0C, and up to 1 year at -80 ^0C. After validation using Omicron XBB. 1.5 rS protein, cross-reactivity was demonstrated with the SARS-CoV-2 variant JN. 1. This validated IgA assay can be a valuable tool to assess mucosal IgA levels in SARS-CoV-2 clinical trials.
| Concepts | Keywords |
|---|---|
| Elisa | assay validation |
| Immunoglobulin | correlate of protection |
| Saliva | COVID-19 |
| Stable | immunogenicity |
| Weeks | Omicron XBB.1.5 |
| SARS-CoV-2 |
Semantics
| Type | Source | Name |
|---|---|---|
| drug | DRUGBANK | Methionine |
| disease | MESH | COVID-19 |