Development and validation of different indirect ELISAs for MERS-CoV serological testing

Area of Science:

• Virology
• Immunology
• Epidemiology

Background:

• Middle East respiratory syndrome coronavirus (MERS-CoV) has caused significant morbidity and mortality globally since 2012, with Saudi Arabia being the most affected country.
• Current serological assays for MERS-CoV detection often require specialized equipment, high-containment facilities, and trained personnel, posing challenges for resource-limited regions.
• There is a need for accessible and reliable diagnostic tools for MERS-CoV seroepidemiological surveillance.

Purpose of the Study:

• To develop and evaluate indirect enzyme-linked immunosorbent assays (ELISAs) using different MERS-CoV antigens for serological testing.
• To compare the performance of developed ELISAs against the gold standard microneutralization (MN) assay.
• To assess the suitability of these ELISAs for MERS-CoV surveillance in endemic areas.

Main Methods:

• Development of three indirect ELISAs utilizing MERS-CoV nucleocapsid protein (N), full spike protein ectodomain (S), and S1 subunit (S1).
• Evaluation of ELISAs using a large cohort of confirmed MERS-CoV seropositive (79) and seronegative (274) human serum samples.
• Comparative analysis of ELISA performance, including sensitivity, specificity, and correlation with the MN assay.

Main Results:

• Both recombinant S1 (rS1)-ELISA and recombinant S (rS)-ELISA demonstrated high sensitivity and specificity (≥90%) across a broad range of optical density values.
• The rS1- and rS-based ELISAs exhibited superior agreement and correlation with the MN assay compared to the rN-ELISA.
• The rN-ELISA showed lower performance metrics in comparison.

Conclusions:

• Recombinant S1 and S protein-based ELISAs are reliable alternatives for MERS-CoV serological testing.
• These developed ELISAs offer a practical and accurate solution for seroepidemiological surveillance in MERS-CoV endemic regions, overcoming limitations of existing methods.
• The findings support the use of rS1-ELISA and rS-ELISA for broader MERS-CoV surveillance efforts.