key: cord-0966414-p0ji20px
authors: Freeman, James; Conklin, Justin; Oramus, Diana; Cycon, Kelly
title: Serology testing demonstrates that antibodies to SARS-CoV-2 S1-RBD correlate with neutralization of virus infection of Vero E6 cells
date: 2021-04-02
journal: J Appl Lab Med
DOI: 10.1093/jalm/jfab027
sha: 5924a93287f244613cc0f055e6bae351dbc631d7
doc_id: 966414
cord_uid: p0ji20px

nan

Coronavirus disease 2019 (COVID-19) patients develop antibodies against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) proteins, including the highly immunogenic Spike (S) and Nucleocapsid (N) proteins used in most serology assays. The S-protein S1-domain harbors the receptor-binding domain (S1-RBD) that targets its cellular receptor, ACE2. Receptor binding is followed by viral fusion, cell entry, and viral replication. Studies have shown that anti-SARS-CoV-2 antibodies are elicited in COVID-19 patients, and that antibody neutralizing activity predominantly targets S1-RBD and total S-protein.

Several groups have reported correlations of neutralizing antibody titers with SARS-CoV-2 and various anti-RBD or anti-S IgG (or total IgG) assay titers [1] [2] [3] [4] ; and, immune and neutralizing titers have correlated strongly with disease severity-the highest titers found in patients with the most severe disease [3] [4] [5] . Current mRNA, DNA, and protein vaccines target Sprotein as antigen, known to elicit neutralizing titers in vaccinated individuals. Such neutralizing antibodies can potentially prevent viral infection by blocking receptor binding-although the level required for immune protection is not yet known.

On July 31, 2020, the Atellica ® IM SARS-CoV-2 IgG (COV2G) Assay Correlations between immune and neutralizing titers and disease severity, as reported by others [3] [4] [5] , could not be assessed due to small sample size (severity level only available for four patients). However, this is a goal for future studies-relevant to populations that may benefit from this kind of serology testing as a proxy for neutralization titers. No correlation was found between Index Value to days from symptom onset or days from RT-PCR positive result.

To our knowledge, these data are the first to demonstrate that COV2G test results correlate with in vitro neutralization using CPE. Future studies should determine whether serology assays can be a suitable substitute for cumbersome 'gold-standard' plaque-reduction neutralization tests 

Robust neutralizing antibodies to SARS-CoV-2 infection persist for months

The receptor binding domain of the viral spike protein is an immunodominant and highly specific target of antibodies in SARS-CoV-2 patients

Defining the features and duration of antibody responses to SARS-CoV-2 infection associated with disease severity and outcome

A longitudinal study of SARS-CoV-2-infected patients reveals a high correlation between neutralizing antibodies and COVID-19 severity

Disease severity dictates SARS-CoV-2-specific neutralizing antibody responses in COVID-19