Magnetic bead-based ELISA allow inexpensive, rapid and quantitative detection of human antibodies against SARS-CoV-2

Abstract

Here we describe a novel immunogenic method to detect COVID-19. The method is a chromogenic magnetic bead-based ELISA which allows inexpensive and quantitative detection of human IgG or IgM antibodies against SARS-CoV-2 in serum or whole blood samples in just 12 minutes. As a proof of concept, we compared the performance of our new method to classical ELISA. Person correlation between optical densities obtained using the two methods was 0.98. The novel magnetic bead-based ELISA performed better than classic ELISA to discriminate one COVID-19 case carrying low antibody titer. The chromogenic magnetic bead-based ELISA method described here can be applied in formats for both point of care and high throughput analysis. The method is readily adaptable to use other protein-based antigens and is readily adaptable to investigate other diseases and other applications.

Antigen production and development of an indirect ELISA based on the nucleocapsid protein to detect human SARS-CoV-2 seroconversion

“…A codon optimized synthetic gene was obtained and cloned into the pET28a vector to allow the expression of an N-terminal 6xHis tagged SARS-CoV-2 N-protein in Escherichia coli BL21 (λDE3) [ 5 , 6 ].The viral protein was highly expressed and remained partially soluble in E. coli cell extracts (Fig. 1A ).…”

Antigen production and development of an indirect ELISA based on the nucleocapsid protein to detect human SARS-CoV-2 seroconversion

“…A codon optimized synthetic gene was obtained and cloned into the pET28a vector to allow the expression of an N-terminal 6xHis tagged SARS-CoV-2 N protein in Escherichia coli BL21 (λDE3) (Huergo et al ., 2020; F. Huergo et al ., 2021). The viral protein was highly expressed and remained partially soluble in E. coli cell extracts (Fig.…”

“…A codon optimized synthetic gene expressing the full-length SARS-CoV-2 N-protein (Uniprot QHD43423.2) was obtained and cloned into pET28a by General Biosystems (F. Huergo et al ., 2021). This plasmid was named pLHSarsCoV2-N and transformed into E. coli BL21 (λDE3) enabling the expression of N-terminal His-tagged N-protein after induction with IPTG.…”

Dimerization of SARS-CoV-2 nucleocapsid protein affects sensitivity of ELISA based diagnostics of COVID-19

“…Despite being present within the viral particle and not very exposed to the surface, SARS-CoV-2 infected patients show elevated and earlier humoral response to the N protein rather than the spike 17 . This is the reason why the N protein is being widely used in vaccine development and serological assays 17–19 . It has been shown for SARS-CoV that the C-terminal region of the N protein is crucial for eliciting antibodies in immunological process 20 .…”