A SARS-CoV-2 surrogate virus neutralization test based on antibody-mediated blockage of ACE2–spike protein–protein interaction

TLDR

The conventional virus neutralization test requires live virus and a biosafety level 3 laboratory. The study aims to develop a surrogate virus neutralization test that detects neutralizing antibodies against the SARS‑CoV‑2 spike protein, enabling assessment of infection rates, herd immunity, and vaccine efficacy without live virus. The assay uses antibody‑mediated inhibition of ACE2–RBD binding to detect neutralizing antibodies in a rapid, isotype‑independent format. Validation in two international cohorts showed 99.93 % specificity and 95–100 % sensitivity, with the assay distinguishing SARS‑CoV‑2 from other coronaviruses and eliminating the need for biosafety level 3 facilities.

Abstract

A robust serological test to detect neutralizing antibodies to SARS-CoV-2 is urgently needed to determine not only the infection rate, herd immunity and predicted humoral protection, but also vaccine efficacy during clinical trials and after large-scale vaccination. The current gold standard is the conventional virus neutralization test requiring live pathogen and a biosafety level 3 laboratory. Here, we report a SARS-CoV-2 surrogate virus neutralization test that detects total immunodominant neutralizing antibodies targeting the viral spike (S) protein receptor-binding domain in an isotype- and species-independent manner. Our simple and rapid test is based on antibody-mediated blockage of the interaction between the angiotensin-converting enzyme 2 (ACE2) receptor protein and the receptor-binding domain. The test, which has been validated with two cohorts of patients with COVID-19 in two different countries, achieves 99.93% specificity and 95-100% sensitivity, and differentiates antibody responses to several human coronaviruses. The surrogate virus neutralization test does not require biosafety level 3 containment, making it broadly accessible to the wider community for both research and clinical applications.