You will find no articles concerning the clinical performance of the Leinco and TECO assays. specificity ranged from 73.9 to 91.3%. Weighted kappa shown a substantial to almost perfect agreement. The findings of our study R428 allow these assays to be considered when a PRNT is not available. However, the second option still should be the favored choice. For optimal medical performance, the cut-off value of the TECO assay should be separately adapted. Keywords: SARS-CoV-2, surrogate ELISA, PRNT, neutralizing antibodies 1. Intro The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the ongoing coronavirus disease 2019 (COVID-19), which was 1st reported in Wuhan, China in late 2019 [1,2]. As of mid-March 2021, confirmed SARS-CoV-2 infections exceeded 119 million worldwide and cases continue to rise [3]. Despite the early detection of new infections and rigorous illness control measures, the presence or absence of protecting immunity will impact future spread, illness severity, and public health response [4]. In a large study carried out in Israel, the recently available BNT162b2 mRNA Covid-19 Vaccine (BioNTech/Pfizer) reduced the risk of symptomatic COVID-19 disease by 94% and the risk of asymptomatic SARS-CoV-2 illness by 90% [5]. This suggests that vaccinated individuals are less likely to transmit the pathogen. However, to date, you will find limited data within the period and nature of immunity generated in response to SARS-CoV-2 illness or after vaccination. To measure the humoral mediated immune response caused by SARS-CoV-2, several commercially available and laboratory-developed antibody checks have been founded [6,7,8]. The level of sensitivity and specificity of these assays vary widely, depending on the used technology, recognized antibody class, disease severity, and instant of screening in the infection phase. The plaque reduction neutralization test (PRNT) is one of the favored methods for the detection of practical, coronavirus-specific neutralizing antibodies from serum samples [9]. Neutralizing antibodies most commonly target the receptor-binding R428 website (RBD) region of the SARS-CoV-2 spike (S) protein, block viral access, and are consequently of particular desire for determining whether antibodies present protecting immunity [10]. However, the PRNT is definitely a biological assay that is hands-on- and time-intensive and may only become performed for smaller sample sizes by experienced staff inside a BSL-3 laboratory. Sample throughput may be improved by using microneutralization assays. Pseudovirus-based neutralization assays use replication deficient computer virus and don’t require former safety measures [11,12,13]. They are also widely used and approved, but they will also be labor-intensive and not suitable for the analysis of a large cohort of subjects. On the other hand, surrogate enzyme-linked immunosorbent assays (sELISAs) have been developed or are under development [14]. These assays work according to the basic principle of competitive binding: anti-SARS-CoV-2 neutralizing antibodies block an enzyme-labeled S-RBD protein from binding its natural ligand, the angiotensin-converting enzyme 2 (ACE2), pre-coated on a microtiter plate. Surrogate ELISAs are hWNT5A high-throughput capable and can become performed under standard laboratory safety conditions [15,16]. However, you will find limited data on their performance when screening specimens of individuals with past SARS-CoV-2 illness or follow-up samples of SARS-CoV-2 vaccinated individuals and especially how they compare to the PRNT. The aim of our study was to evaluate the clinical overall performance of three manual surrogate ELISAs and one automated quantitative SARS-CoV-2 S protein-based IgG antibody assay by comparing test results to the PRNT carried out in parallel. We analyzed serum follow-up samples taken R428 at different timepoints of.