However, we note that this technique has been used by other groups and thus offers a high degree of generalizability with other results [24, 25]. The cPass assay detected all specimens with positive WT PRNT-90 titers, with a significant proportion of false positives (Figure 1). across intervals from onset of symptoms of SARS-CoV-2 contamination. Results Compared with PRNT-50, cPass sensitivity ranged from 77% to 100% and specificity was 95% to 100%. Sensitivity was also high compared with the pseudotyped lentiviral neutralization assay (93%; 95% confidence interval [CI], 85C97), but specificity was lower (58%; 95% CI, 48C67). Highest agreement between cPass and ELISA was for anti-RBD IgG (= 0.823). Against the pseudotyped lentiviral neutralization assay, anti-RBD IgG sensitivity (99%; 95% CI, 94C100) was very similar to that of cPass, but overall specificity was lower (37%; 95% CI, 28C47). Against PRNT-50, results of cPass and anti-RBD IgG were nearly identical. Conclusions The added SIRT-IN-1 value of cPass compared with an IgG anti-RBD ELISA was modest. Keywords: COVID-19, ELISA, neutralizing antibodies, SARS-CoV-2, Serology The results of the current evaluation demonstrate the ability of cPass SARS-CoV-2 Neutralization Antibody Detection Kit (GenScript) to detect blood specimens with anti-SARS-CoV-2 neutralizing antibodies. However, the added value of the cPass compared with an IgG anti-RBD ELISA was modest. Use cases for serological screening for prior exposure to severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) have been reviewed in detail [1, 2]. Despite a rapid increase in the number and availability of serological assays detecting SARS-CoV-2 antibodies, critical knowledge gaps remain regarding the magnitude and kinetics of the correlation between results of these assays and the presence of neutralizing antibodies. Only a subset of antibodies against a specific antigen can neutralize viral replication. Assays that measure neutralizing antibody levels, Rabbit polyclonal to TDGF1 such as plaque reduction neutralization assessments (PRNT) and microneutralization methods, provide essential data; these assays can help validate candidate diagnostic assessments and define serological correlates of immunity. However, functional cell-based assays of SARS-CoV-2 neutralization can only be performed in a Biosafety Level (BSL)-3 laboratory, which is usually labor-intensive, costly, and limits screening throughput. Pseudotyped viruses have been developed that incorporate the spike protein of SARS-CoV-2 and can be cultivated in BSL-2 conditions [3]. Assays incorporating such pseudotyped viruses provide a functional assessment of the host neutralizing antibody responses as an alternative to using the wild-type (WT) computer virus [4C7]. By contrast, surrogates of neutralization that bypass the need for viral culture would offer substantial advantages in terms of throughput, cost, and scalability. At least 1 direct enzyme-linked immunosorbent assay (ELISA) detecting antibodies to the whole spike protein has received regulatory approval in Europe for assessment of neutralizing antibodies [8]. Furthermore, several groups have proposed blocking assays, leveraging different transmission detection methods to quantify the presence of host antibodies that can block the conversation of the SARS-CoV-2 spike protein with human angiotensin-converting enzyme (ACE)-2 receptor [9C12]. On November 6, 2020, the US Food and Drug Administration (FDA) issued an emergency use authorization (EUA) for the cPass SARS-CoV-2 Neutralization SIRT-IN-1 Antibody Detection Kit (cPass; GenScript, Piscataway, NJ) [13], which is the first such surrogate neutralization assay to be commercially available. The cPass uses a blocking ELISA format with human ACE-2 receptor molecules coated on an ELISA plate [9, 14]. Human sera preincubated with labeled epitopes of the receptor-binding domain name (RBD on S1 proteins) are then transferred to the plate. This blocking ELISA serves as a surrogate assay to inform on the capacity of human sera to block the interaction between the spike fusion protein (through its RBD) and its cellular receptor ACE-2. The objective of this study was to inform the use of the cPass and assess its added value compared with laboratory-developed anti-RBD ELISA assays by performing an evaluation using a variety of well characterized specimens. Several reference panels were used to better understand the ability of the cPass assay to detect significant titers of neutralizing antibodies assessed by culture-based reference methods. We compared cPass to PRNT and to a pseudotyped computer virus neutralization assay. We also sought to describe the correlation of cPass with a laboratory-developed indirect ELISA detecting anti-RBD IgG, IgM, and IgA antibodies at a single timepoint and across different time frames among specimens collected at a known interval from onset of symptoms of SARS-CoV-2 contamination. METHODS Ethics All work was conducted in accordance with the Declaration of Helsinki in terms of informed consent and approval by an appropriate institutional board. Convalescent plasmas were obtained from donors SIRT-IN-1 who consented to participate in this research project at Hma-Qubec, the agency responsible for blood supply in Quebec, Canada (Research Ethics Table [REB] no. 2020-004) and the Centre de Recherche du Centre Hospitalier de lUniversit de Montral ([CR-CHUM] REB no. 19.381). The donors met all donor eligibility criteria: previous confirmed coronavirus disease 2019 (COVID-19) contamination and complete resolution of symptoms for at least 14 days. At the.