Peptide microarray based analysis of antibody responses to SARS-CoV-2 identifies unique epitopes with potential for diagnostic test development

Abstract

SummaryHumoral immunity to the Severe Adult Respiratory Syndrome (SARS) Coronavirus (CoV)-2 is not fully understood yet but may be a crucial factor of immune protection. The possibility of antibody cross-reactivity between SARS-CoV-2 and other human coronaviruses (HCoVs) would have important implications for immune protection but also for the development of specific diagnostic ELISA tests. Using peptide microarrays, n=24 patient samples and n=12 control samples were screened for antibodies against the entire SARS-CoV-2 proteome as well as the Spike (S), Nucleocapsid (N), VME1 (V), R1ab, and Protein 3a (AP3A) of the HCoV strains SARS, MERS, OC43 and 229E. While widespread cross-reactivity was revealed across several immunodominant regions of S and N, IgG binding to several SARS-CoV-2-derived peptides provided statistically significant discrimination between COVID-19 patients and controls. Selected target peptides may serve as capture antigens for future, highly COVID-19-specific diagnostic antibody tests.

Cross-reactive CD4+ T cells enhance SARS-CoV-2 immune responses upon infection and vaccination

“…4C). Antibodies to the SARS-CoV-2 spike amino acid residues 815-823 (peptide 204_-1) were previously reported in COVID-19 patients but also in unexposed individuals (21). By examining sera from iCope-T-cell-assay-responders and non-responders we detected 204_-1 binding antibodies in all individuals, however, significantly higher concentration of these antibodies was found in COVID-19 convalescents with substantially more iCope-reactive T cells (Fig.…”

“…The high allele frequencies of HLA-DPA1*01:03 and, in particular, HLA-DPB1*04:01 as well as increased homozygosity among responders in our population may explain why so many individuals were able to raise a T cell response to iCope and its homologues in other HCoVs. Of note, IgG screening against spike and nucleocapsid specific epitopes revealed high responses in COVID-19 convalescents as well as multiple cross-reactive responses in healthy donors for a sequence containing the SARS-CoV-2 B cell epitope SFIEDLLF (21) present in iCope and overlapping 73% with iCope. SARS-CoV-2 infection and vaccination with BNT162b2 induced specific antibody production towards this region.…”

Peptide epitope-imprinted polymer microarrays for selective protein recognition. Application for SARS-CoV-2 RBD protein

“…36,37 Hence we present here the first epitope-based MIP and this concept may be adapted towards the recognition of different virus mutants and discriminating between closely homologue proteins. 38 Scheme 1 Simplified workflow of the epitope-imprinted polymer synthesis and SPRi-based characterization. The selected nonapeptide epitope for the RBD of S protein (GFNCYFPLQ) bearing a central cysteine (and other relevant peptides, e.g.…”

Experimental Identification of Immuno- dominant B-cell Epitopes from SARS-CoV-2

“…The proposed peptides are: S769-786 + N153-170 (Amrun et al [32] ), N386-406 + S810-830 + S1146-1166 (Shrock et al [39] ), S1143-1165 (Mishra et al [25] ), S1148-1159 + 577-588 (Li et al [22] ), N155-171 (Musico et al [24] ), N377-407/S557-567/S789-799 (Holenya et al [26] ) and M1-24 (Heffron et al [27] ).…”

“…Furthermore, a peptide with low homology to other common coronaviruses, such as the ones responsible for common colds, can lead to higher specificity of the test. [9] Understanding which parts of a protein lead to neutral- arrays: (i) spotting biotinylated peptides into a streptavidin coated microarray, [18,19] (ii) spotting peptide-BSA conjugates, [20][21][22] (iii) hybridizing of peptide-PNA conjugates into DNA microarrays, [23] (iv) spotting alkyne-tagged peptides that are immobilized by CuAAC into an azide-coated microarray, [24] (v) by directly printing the peptide into the microarray [25,26] and other non-disclosed methodologies (performed by CRO). [27][28][29][30] For the ELISA-based approaches, Poh et al (vi) firstly made pools of 5-8 different peptides to identify pools of candidates and refine further analysis of singleton peptides in a deconvolution step, [31,32] whereas Zhang et al (vii) directly analyzed all the peptides individually.…”