# Development of an ELISA Using Recombinant Chimeric SM Protein for Serological Detection of SARS-CoV-2 Antibodies

## TL;DR

This paper describes the development of a new ELISA test using a chimeric protein to detect SARS-CoV-2 antibodies with high accuracy.

## Contribution

The first domestic ELISA test system using a recombinant chimeric SM protein for SARS-CoV-2 antibody detection is developed.

## Key findings

- The ELISA achieved 90.48% sensitivity and 93.65% specificity in antibody detection.
- The test system demonstrated high diagnostic accuracy with an AUC of 0.9623 and a positive diagnostic ratio of 14.25.

## Abstract

The emergence and spread of coronavirus infections have created a necessity to develop serological methods for assessing population immunity. The enzyme-linked immunosorbent assay (ELISA) remains one of the most accessible and informative approaches for these purposes. The choice of recombinant proteins plays an important role in the sensitivity and specificity of the test system, and in this regard, the creation of a domestic ELISA based on the chimeric SM protein to the SARS-CoV-2 virus is relevant. In this work, a recombinant chimeric SM protein expressed in the E. coli system and purified using metal-affinity chromatography on Ni-NTA agarose was constructed and presented for the first time. An ELISA test system was developed and tested using panels of positive and negative sera, including samples obtained before the COVID-19 pandemic. The obtained sensitivity (90.48%) and specificity (93.65%) indicators with a ROC curve AUC = 0.9623 (OD450 = 0.213) indicate the diagnostic accuracy of the test system. The positive diagnostic ratio (LR+) = 14.25.0 indicates the reliability of a positive result. The domestically developed ELISA test system can be used for serological monitoring and assessment of the immune status of the population.