Red dotted line = manufacturers positive cut-off at 33.8 BAU/mL. Seropositive samples, defined by an S-IgG concentration Hyperforin (solution in Ethanol) of 33.8 BAU/mL, showed a positive result in our neutralization assay with a titer of 10 in 94.8% (110/116) of tested Hyperforin (solution in Ethanol) samples. 4. of S-IgG levels in predicting neutralization capacity, with 94.8% Hyperforin (solution in Ethanol) of seropositive samples showing a neutralization titer of 10, making it a viable yet cheap and easy-to-determine surrogate parameter for neutralization capacity. Keywords: SARS-CoV-2, COVID-19, vaccination, neutralization, serology, antibodies, immunity 1. Introduction The ongoing pandemic of SARS-CoV-2 maintains threatening not only individual and public health but leaves its mark on almost every aspect of our lives today. As of 22 August 2021, more than 200 million confirmed cases have been reported, causing over 4 million deaths worldwide [1]. Global efforts have brought forth several vaccines with different mechanisms of action, and with over 4 billion doses administered [1], a significant part of the worlds populace has developed humoral and cellular immunity against the computer virus. Measuring the immune response against SARS-CoV-2 both after contamination and after vaccination will help guide the next necessary steps to control the pandemic. Vaccination has proven an effective tool in the prevention of SARS-CoV-2 infections [2,3]. Both vector-based and mRNA-based vaccines approved by the European Medicines Agency generate a potent humoral and cellular immunity [4,5,6,7], inducing high levels of antibodies detectable in different assay systems. In this study, we focused on assessing serum neutralization capacity and S-IgG antibody response longitudinally after SARS-CoV-2 contamination or after vaccination. While CD4+ and CD8+ T-cells also contribute to immunity against SARS-CoV-2 [8,9], several studies exhibited the importance of SARS-CoV-2-specific neutralizing antibodies as a protection mechanism against severe contamination [10,11], with S-IgG found in almost every patient after contamination. Longitudinal data of antibody concentrations for the first 6C10 Mouse monoclonal to FBLN5 months after contamination exists in abundance [10,11,12,13], while evidence around the persistence of humoral immunity a 12 months after the contamination has only begun to emerge recently [14]. We used a commercial S-IgG chemiluminescence immunoassay (CLIA) and established a neutralization assay based on cell culture to demonstrate longitudinal courses of neutralizing antibody concentrations both after contamination, or after vaccination to further investigate the persistence of long-term humoral immunity. 2. Materials and Methods 2.1. Study Collective For this study, we acquired serum samples of 40 participants (m:f 21:19, median age 64, interquartile range (IQR) 53C72) infected with SARS-CoV-2 in March 2020 during one of the first outbreaks of SARS-CoV-2 in Germany in Neustadt am Rennsteig. Serum samples were initially acquired 6 weeks after a mass screening took place as part of the CoNAN study that has been described in detail in [15]. Additional follow-ups 6 months and 12 months after the initial sampling took place to enable long-term longitudinal analysis. In addition, we recruited two groups of participants from the staff of Jena University Hospital, who received their initial vaccinations between December 2020 and February 2021. The first, homologous vaccination group (= 22, m:f 6:16, median age 45, IQR 30C53) received a primary vaccination with BNT162b2 (BioNTech, Mainz, Germany) and booster vaccination with the same vaccine after 3 weeks. The second, heterologous vaccination group (= 21, m:f 5:16, median age 36, IQR 32C44) received a primary vaccination with the vector-based vaccine AZD1222 (AstraZeneca, Cambridge, UK) and booster vaccination with either mRNA-1273 (Moderna, Cambridge, USA) or BNT162b2 after 12 weeks. For both vaccination groups, serial serum samples were acquired at pre-defined dates (0, 1, 2, 3, 4, 5, 8, and 16 weeks after primary vaccination). More detailed information about the study collective can be found in Supplementary Tables S1 and S2. 2.2. Serological Assay Serological analyses for SARS-CoV-2 S-IgG antibodies were performed using the Liaison SARS-CoV-2 TrimericS IgG CLIA around the LiaisonXL (DiaSorin, Saluggia, Italy) following the manufacturers instructions. According to the manufacturers instruction for use, this assay detects IgG antibodies against SARS-CoV-2-specific trimeric Spike glycoprotein with an estimated sensitivity of 98.7% (153/155) at 15 days after the first positive RT-PCR, and an estimated specificity of 99.5% (1889/1899). Samples were defined as seropositive for determining values of 33.8 BAU/mL. The manufacturer says that seropositive samples showed a positive agreement of 100% (Wilson 95% CI: 97.8C100%) with a neutralization titer of 1 1:10 in a micro-neutralization assay, while.