Egg yolk immunoglobulin (IgY) targeting SARS-CoV-2 S1 as potential virus entry blocker.

AIMS: COVID-19 pandemic caused by SARS-CoV-2 has become a public health crisis worldwide. In this study, we aimed at demonstrating the neutralizing potential of the IgY produced after immunizing chicken with a recombinant SARS-CoV-2 spike protein S1 subunit. METHODS AND RESULTS: E. coli BL21 carrying plasmid pET28a-S1 was induced with IPTG for the expression of SARS-CoV-2 S1 protein. The recombinant His-tagged S1 was purified and verified by SDS-PAGE, Western blot and biolayer interferometry (BLI) assay. Then S1 protein emulsified with Freund's adjuvant was used to immunize layer chickens. Specific IgY against S1 (S1-IgY) produced from egg yolks of these chickens exhibited a high titer (1:25,600) and a strong binding affinity to S1 (KD  = 318 nmol L-1 ). The neutralizing ability of S1-IgY was quantified by a SARS-CoV-2 pseudotyped virus-based neutralization assay with an IC50  value of 0.99 mg ml-1 . In addition, S1-IgY exhibited a strong ability in blocking the binding of SARS-CoV-2 S1 to hACE2, and it could partially compete with hACE2 for the binding sites on S1 by BLI assays. CONCLUSIONS: We demonstrated here that after immunization of chickens with our recombinant S1 protein, IgY neutralizing antibodies were generated against the SARS-CoV-2 spike protein S1 subunit; therefore, showing the potential use of IgY to block the entry of this virus. SIGNIFICANCE AND IMPACT OF THE STUDY: IgY targeting S1 subunit of SARS-CoV-2 could be a promising candidate for pre- and post-exposure prophylaxis or treatment of COVID-19. Administration of IgY-based oral preparation, oral or nasal spray may have profound implications for blocking SARS-CoV-2.

Exploring the potential usefulness of IgY for antiviral therapy: A current review.

Immunoglobulin yolk (IgY) is therapeutic antibodies presented in yolk eggs of birds, reptiles, and amphibians. These proteins produced by the immune system of the animal, are capable of neutralizing antigenic molecules, including viral antigens, fulfilling a role in the body defense. The specificity of these antibodies and the facility for their production, make these molecules capable of being used as tools for diagnosis and immunotherapy. Regarding this last aspect, it is common knowledge that the field of virology, is racing against time in the development of new drugs and vaccines to try to contain pandemics and local epidemics and, in counterproposal, avian antibodies are neutralizing molecules that can help in the control and spread of disease. These molecules have been explored for years and currently chicken eggs are produced in large quantities from the animal's immunization against a specific pathogen. Thus, on this subject, this review made a survey of these researches and presents a summary of all the successful cases and perspectives in the use of IgYs as tools for viral immunization.

The preparation of N-IgY targeting SARS-CoV-2 and its immunomodulation to IFN-γ production in vitro.

Specific antibodies against SARS-CoV-2 structural protein have a wide range of effects in the diagnose, prevention and treatment of the COVID-19 epidemic. Among them, egg yolk immunoglobulin Y (IgY), which has high safety, high yield, and without inducing antibody-dependent enhancement, is an important biological candidate. In this study, specific IgY against the conservative nucleocapsid protein (NP) of SARS-CoV-2 was obtained by immunizing hens. Through a series of optimized precipitation and ultrafiltration extraction schemes, its purity was increased to 98%. The hyperimmune IgY against NP (N-IgY) at a titer of 1:50,000 showed strong NP binding ability, which laid the foundation of N-IgY's application targeting NP. In an in vitro immunoregulatory study, N-IgY (1 mg/mL) modulated NP-induced immune response by alleviating type II interferon secretion stimulated by NP (20 µg/mL). In summary, N-IgY can be mass produced by achievable method, which endows it with potential value against the current COVID-19 pandemic.