Peptide Epitope-Based Avian IgY Antibodies against SARS-CoV-2 Spike: A Cost Effective Approach for Viral Detection and Neutralization

Abstract

Background: Peptides offer a rapid, scalable, cost-effective platform for developing targeted diagnostic and therapeutic tools due to their ease of synthesis, structural versatility, and high specificity. Although the acutephase of the COVID-19 pandemic has eased, the emergence of SARS-CoV-2 variants continues to be public health concern. In this context, peptide epitope-based antibodies targeting the viral spike protein remain central to virus detection and neutralization, providing a promising alternative to traditional protein-based approaches. Methods and results: This study describes a structure-guided, peptide epitope-based strategy to generate polyclonal avian IgY antibodies targeting the SARS-CoV-2 spike protein. Five immunogenic peptides (PEP1–PEP5), selected based on surface accessibility and antigenicity, were synthesized and used to immunize chickens. The resulting antibodies were extracted from egg yolks using a scalable polyethylene glycol precipitation method. Among the generated antibodies, those raised against PEP2, PEP5, and their combination exhibited high titers (up to 1: 64,000) and strong reactivity against recombinant spike protein under both native and denaturing conditions. In sandwich ELISA using pre-validated patient swab samples, these IgY antibodies showed specific reactivity with COVID-19 positive samples. Importantly, virus neutralization assays demonstrated that co-incubation with the IgY antibodies resulted in over 90% reduction in SARS-CoV-2 infection, highlighting their therapeutic efficacy. Conclusion: This study demonstrates a rapid, sustainable, cost-effective approach for generating IgY antibodies using peptide epitopes instead of full-length or recombinant spike domains. The resulting antibodies show high diagnostic specificity and strong viral neutralization, highlighting their dual potential and value as tools for SARS-CoV-2 and other evolving viral threats.