Novel quantitative enzyme linked immunosorbent assay to detect RBD and Spike protein of SARS-COV-2 useful for diagnosis of COVID-19

JUAN IGNACIO MARFIA; ADRIANA SABLIJIC; SILVINA SONIA BOMBICINO; ALDANA TRABUCCHI; RUBÉN FRANCISCO IACONO; IGNACIO SMITH; GREGORIO JUAN MC CALLUM; FEDERICO JAVIER WOLMAN; ALEXANDRA MARISA TARGOVNIK; JOAQUÍN POODTS; MATÍAS FINGERMANN; ADOLFO DE ROODT; MARCELO RODRIGUEZ FERMEPIN; LUCIA GALLO VAULET; LEONARDO GABRIEL ALONSO; MARÍA VICTORIA MIRANDA; SILVINA VALDEZ

Mar del Plata

Congreso; Reunión Anual de Sociedades de Biociencias SAIC, SAI&FAIC, SAFIS; 2022

Herein we describe a novel enzyme-linked immunosorbent assay (ELISA) for SARS-CoV-2 antigen detection employing a high affinity polyclonal serum to recombinant Spike (S) protein, which was produced at high scale in horse. This assay is aimed for diagnosis of COVID-19 and quantification of RBD and S protein from any production process.Materials and methods: Equine polyclonal anti-S antibodies were obtained by immunization of one mixed-breed 4 to 10 years-old, 300 to 450 kg horse. The purified antibodies were incubated with a 20-fold molar excess of sulfo-NHS-biotin. Free biotin was removed on a PD-10 desalting column. The ELISA was based on the capture of the antigen present in samples or calibration curve by equine anti-S antibodies immobilized in the solid phase. Bound RBD or S protein was detected by the addition of antibodies anti-S-biotin followed by Streptavidin-Horseradish Peroxidase. Twenty human samples from the respiratory tract were analyzed in parallel by rRT-PCR and by ELISA. Additionally, recombinant S protein or RBD both expressed in baculovirus/ insect larvae were detected and quantified.