Multiepitope Proteins for the Differential Detection of IgG Antibodies against RBD of the Spike Protein and Non-RBD Regions of SARS-CoV-2.

Larissa R Gomes,David W Provance,Mariana S Freitas,Jéssica S Furtado,Carlos M Morel,Paloma Napoleão-Pêgo,Natalia Fintelman-Rodrigues,Mario C R Machado,Romário G Aquino,Thiago M L Souza,Nathalia B R De Sá,Andressa M Durans,Lilian V Pereira,Salvatore G De-Simone,Jessica A Waterman

doi:10.3390/vaccines9090986

Larissa R Gomes, David W Provance + Show 13 more

Open Access

https://doi.org/10.3390/vaccines9090986

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Abstract

The COVID-19 pandemic has exposed the extent of global connectivity and collective vulnerability to emerging diseases. From its suspected origins in Wuhan, China, it spread to all corners of the world in a matter of months. The absence of high-performance, rapid diagnostic methods that could identify asymptomatic carriers contributed to its worldwide transmission. Serological tests offer numerous benefits compared to other assay platforms to screen large populations. First-generation assays contain targets that represent proteins from SARS-CoV-2. While they could be quickly produced, each actually has a mixture of specific and non-specific epitopes that vary in their reactivity for antibodies. To generate the next generation of the assay, epitopes were identified in three SARS-Cov-2 proteins (S, N, and Orf3a) by SPOT synthesis analysis. After their similarity to other pathogen sequences was analyzed, 11 epitopes outside of the receptor-binding domain (RBD) of the spike protein that showed high reactivity and uniqueness to the virus. These were incorporated into a ß-barrel protein core to create a highly chimeric protein. Another de novo protein was designed that contained only epitopes in the RBD. In-house ELISAs suggest that both multiepitope proteins can serve as targets for high-performance diagnostic tests. Our approach to bioengineer chimeric proteins is highly amenable to other pathogens and immunological uses.

Highlights

Emerging infectious diseases are a global public health challenge [1]
Two studies have shown that the transmission of SARS-CoV-2 before the beginning of symptoms can vary by 12.6% [5] and 65% [6], which makes up the majority (~86%) of infected people [7]
We identified linear B cell epitopes in the S, N, and ORF3a proteins that were used to bioengineer a chimeric protein containing a high number of epitopes from outside of the receptor-binding domain (RBD) of the S protein (Dx-SARS2-noRBD); achieved by inserting their sequences into the thermal green protein (TGP) to replace the non-ß sheet regions

Summary

Introduction

Emerging infectious diseases are a global public health challenge [1]. First suspected from the outbreak of viral pneumonia cases in residents from the Wuhan region of China [2], the novel disease was determined to be caused by a new coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) [3]. It has a more extended incubation period than SARS-CoV and MERS-CoV [4], which is 5 days on average with a range of 1–14 days before the onset of symptoms. Two studies have shown that the transmission of SARS-CoV-2 before the beginning of symptoms can vary by 12.6% [5] and 65% [6], which makes up the majority (~86%) of infected people [7]

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