doi:10.3390/biology10030208engSantiago, LlipsyUranga-Murillo, IratxeArias, MaykelGonzález-Ramírez, Andrés M.Macías-León, JavierMoreo, EduardoRedrado, SergioGarcía-García, AnaTaleb, VíctorLira-Navarrete, ErandiHurtado-Guerrero, RamónAguilo, Nachodel Mar Encabo-Berzosa, MariaHidalgo, SandraGalvez, Eva M.Ramirez-Labrada, Arielde Miguel, DiegoBenito, RafaelMiranda, PatriciaFernández, AntonioDomingo, José M.Serrano, LauraYuste, CristinaVillanueva-Saz, SergioPaño-Pardo, José R.Pardo, JuliánDetermination of the Concentration of IgG against the Spike Receptor-Binding Domain That Predicts the Viral Neutralizing Activity of Convalescent Plasma and Serum against SARS-CoV-2ART-2021-123857Several hundred millions of people have been diagnosed of coronavirus disease 2019 (COVID-19), causing millions of deaths and a high socioeconomic burden. SARS-CoV-2, the causative agent of COVID-19, induces both specific T- and B-cell responses, being antibodies against the virus detected a few days after infection. Passive immunization with hyperimmune plasma from convalescent patients has been proposed as a potentially useful treatment for COVID-19. Using an in-house quantitative ELISA test, we found that plasma from 177 convalescent donors contained IgG antibodies specific to the spike receptor-binding domain (RBD) of SARS-CoV-2, although at very different concentrations which correlated with previous disease severity and gender. Anti-RBD IgG plasma concentrations significantly correlated with the plasma viral neutralizing activity (VN) against SARS-CoV-2 in vitro. Similar results were found using an independent cohort of serum from 168 convalescent health workers. These results validate an in-house RBD IgG ELISA test in a large cohort of COVID-19 convalescent patients and indicate that plasma from all convalescent donors does not contain a high enough amount of anti-SARS-CoV-2-RBD neutralizing IgG to prevent SARS-CoV-2 infection in vitro. The use of quantitative anti-RBD IgG detection systems might help to predict the efficacy of the passive immunization using plasma from patients recovered from SARS-CoV-2.2021http://zaguan.unizar.es/record/10157610.3390/biology10030208http://zaguan.unizar.es/record/101576oai:zaguan.unizar.es:101576info:eu-repo/grantAgreement/ES/DGA-FEDER/B29-17Rinfo:eu-repo/grantAgreement/ES/DGA-FEDER/E34-R17info:eu-repo/grantAgreement/ES/DGA/LMP58-18info:eu-repo/grantAgreement/ES/ISCIII/COV20-00308info:eu-repo/grantAgreement/ES/MCIU-AEI/SAF2017-83120-C2-1-Rinfo:eu-repo/grantAgreement/ES/MINECO/BFU2016-75633-Pinfo:eu-repo/grantAgreement/ES/MINECO/CTQ2013-44367-C2-2-Pinfo:eu-repo/grantAgreement/ES/MINECO/PID2019-105451GB-I00Biology 10, 3 (2021), 208 [14 pp.]byhttp://creativecommons.org/licenses/by/3.0/es/info:eu-repo/semantics/openAccess