†These authors contributed equally.
Academic Editor: Alessandro Poggi
Background: Several commercial surrogate Virus Neutralization Tests
(sVNTs) have been developed in the last year. Neutralizing anti-SARS-CoV-2
antibodies through interaction with Spike protein Receptor Binding Domain (S-RBD)
can block the virus from entering and infecting host cells. However, there is a
lack of information about the functional activity of SARS-CoV-2 antibodies that
may be associated with protective responses. For these reasons, to counteract
viral infection, the conventional virus neutralization test (VNT) is still
considered the gold standard. The aim of this study was to contribute more and
detailed information about sVNTs’ performance, by determining in vitro
the anti-SARS-CoV-2 neutralizing antibody concentration using four different
commercial assays and then comparing the obtained data to VNT. Methods:
Eighty-eight samples were tested using two chemiluminescence assays (Snibe and
Mindray) and two ELISA assays (Euroimmun and Diesse). The antibody titers were
subsequently detected and quantified by VNT. Results: The overall
agreement between each sVNT and VNT was 95.45% for Euroimmun and 98.86% for
Diesse, Mindray and Snibe. Additionally, we investigated whether the sVNTs were
closer to the gold standard than traditional anti-SARS-CoV-2 antibody assays
S-RBD or S1 based, finding a higher agreement mean value for sVNTs (98.01