Identification of COVID-19 B-cell epitopes with phage-displayed peptide library

Abstract

Background Coronavirus disease 19 (COVID-19) first appeared in the city of Wuhan, in the Hubei province of China. Since its emergence, the COVID-19-causing virus, SARS-CoV-2, has been rapidly transmitted around the globe, overwhelming the medical care systems in many countries and leading to more than 3.3 million deaths. Identification of immunological epitopes on the virus would be highly useful for the development of diagnostic tools and vaccines that will be critical to limiting further spread of COVID-19. Methods To find disease-specific B-cell epitopes that correspond to or mimic natural epitopes, we used phage display technology to determine the targets of specific antibodies present in the sera of immune-responsive COVID-19 patients. Enzyme-linked immunosorbent assays were further applied to assess competitive antibody binding and serological detection. VaxiJen, BepiPred-2.0 and DiscoTope 2.0 were utilized for B-cell epitope prediction. PyMOL was used for protein structural analysis. Results 36 enriched peptides were identified by biopanning with antibodies from two COVID-19 patients; the peptides 4 motifs with consensus residues corresponding to two potential B-cell epitopes on SARS-CoV-2 viral proteins. The putative epitopes and hit peptides were then synthesized for validation by competitive antibody binding and serological detection. Conclusions The identified B-cell epitopes on SARS-CoV-2 may aid investigations into COVID-19 pathogenesis and facilitate the development of epitope-based serological diagnostics and vaccines.

Monoclonal antibodies for COVID-19 therapy and SARS-CoV-2 detection

“…Meanwhile, the S protein plays a significant role in viral fusion and entry into host cells and is composed of S1 RBD at N-terminus and S2 subunits at C-terminus [ 165 ]. Previous reports indicated that both NP and S protein are immunogenic, as Abs against NP and the RBD of S protein as well as their B cell epitopes were readily detected upon early seroconversion in COVID-19 patients [ 166 – 169 ]. ELISAs using NP and RBD of S protein show high specificity and no cross-reactivity with non-CoV, HCoV, MERS-CoV, or SARS-CoV [ 170 , 171 ].…”

Intramuscular injection of a mixture of COVID-19 peptide vaccine and tetanus vaccine in horse induced neutralizing antibodies against authentic virus of SARS-CoV-2 Delta variant

“…Our novel vaccine strategy, i.e., taking advantage of both the adjuvant and the tetanus toxoid in a tetanus vaccine, is different from other COVID-19 peptide vaccine strategies published in the literature, i.e., focusing on B-cell and T-cell epitope identification and adjuvant development [2] , [3] , [4] , [5] , [19] , [20] , [21] , [22] , [23] . Furthermore, we used authentic viruses in neutralization assay whereas others did not.…”

A Promising Tool in Serological Diagnosis: Current Research Progress of Antigenic Epitopes in Infectious Diseases

“…The neo-coronavirus particle consists of an RNA gene chain, four structural proteins (spike (S) protein, small envelope (E) glycoprotein and membrane (M) glycoprotein, nucleocapsid (N) protein) and several auxiliary open reading frame (ORF) proteins. Among them is the S protein [ 88 , 89 , 90 , 91 , 92 , 93 ], which binds to angiotensin-converting enzyme 2 on the surface of human cells and is involved in the fusion and replication of viral and human cells; and the N protein [ 91 , 93 , 94 ], which is relatively conserved and against which the body can produce high levels of antibodies early in infection. These have both become major foci in the development of diagnostic epitopes for new coronaviruses.…”