Large scale production and characterization of SARS‐CoV‐2 whole antigen for serological test development

Cerutti, Helena; Ricci, Veronica; Tesi, Giulia; Soldatini, Claudia; Castria, Marinunzia; Vaccaro, Marco Natale; Tornesi, Stefania; Toppi, Simona; Verdiani, Silvana; Brogi, Alessandra

BACKGROUND: The rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has generated a pandemic with alarming rates of fatality worldwide. This situation has had a major impact on clinical laboratories that have attempted to answer the urgent need for diagnostic tools, since the identification of coronavirus disease 2019 (COVID‐19). Development of a reliable serological diagnostic immunoassay, with high levels of sensitivity and specificity to detect SARS‐CoV‐2 antibodies with improved differential diagnosis from other circulating viruses, is mandatory. METHODS: An enzyme‐linked immunosorbent assay (ELISA) using whole inactivated virus cultured in vitro, was developed to detect viral antigens. WB and ELISA investigations were carried out with sera of convalescent patients and negative sera samples. Both analyses were concurrently performed with recombinant MABs to verify the findings. RESULTS: Preliminary data from 10 sera (5 patients with COVID‐19, and 5 healthy controls) using this immunoassay are very promising, successfully identifying all of the confirmed SARS‐CoV‐2‐positive individuals. CONCLUSION: This ELISA appears to be a specific and reliable method for detecting COVID‐19 antibodies (IgG, IgM, and IgA), and a useful tool for identifying individuals which have developed immunity to the virus.