Robust and low-cost ELISA based on IgG-Fc tagged recombinant proteins to screen for anti-SARS-CoV-2 antibodies

• Published in: Journal of immunological methods Vol. 495; p. 113082
• Main Authors: Frumence, Etienne, Lebeau, Grégorie, Viranaicken, Wildriss, Dobi, Anthony, Vagner, Damien, Lalarizo Rakoto, Mahary, Sandenon Seteyen, Anne-Laure, Giry, Claude, Septembre-Malaterre, Axelle, Raffray, Loïc, Gasque, Philippe
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2021; Elsevier
• Subjects: cell culture; cell lines; CHO cells; chromatography; COVID-19; COVID-19 infection; ELISA; Life Sciences; prices; Recombinant protein; SARS-CoV-2; Serological assay; Severe acute respiratory syndrome coronavirus 2; Technical Note; COVID-19; SARS-CoV-2; Serological assay; Recombinant protein; CHO cells; ELISA
• ISSN: 0022-1759; 1872-7905; 1872-7905
• DOI: 10.1016/j.jim.2021.113082

The development of new diagnostic assays become a priority for managing COVID-19. To this aim, we presented here an in-house ELISA based on the production of two major recombinant and high-quality antigens from SARS-CoV-2. Full-length N and S-RBD fragment proteins fused to mouse IgG2a-Fc were produced in the CHO cell line. Secreted recombinant proteins were easily purified with standard Protein A chromatography and were used in an in-house ELISA to detect anti-N and anti-RBD IgGs in the plasma of COVID-19 RTPCR-positive patients. High reactivity against recombinant antigens was readily detected in all positive plasma samples, whereas no recognition was observed with control healthy subject's plasmas. Remarkably, unpurified recombinant N protein obtained from cell culture supernatant was also suitable for the monitoring by ELISA of IgG levels in positive patients. This work provides an early prospection for low price but high-quality serological kit development. •The full-length N and S-RBD fragment proteins of SARS-COV-2 were produced in the CHO cell line.•Secreted recombinant proteins fused to mouse IgG2a-Fc were easily purified.•Recombinant proteins were readily usable without purification steps in ELISA.•The high quality of these proteins allows the establishment of low cost serological assays.