Preclinical Assessment of a Recombinant RBD-Fc Fusion Protein As SARS-CoV-2 Candidate Vaccine

Overview

Journal Eur J Microbiol Immunol (Bp)

Publisher Akademiai Kiado

Specialty Allergy & Immunology

Date 2024 May 16

PMID 38753442

Authors

Navid Dashti

Forough Golsaz-Shirazi

Haleh Soltanghoraee

Amir-Hassan Zarnani

Mehdi Mohammadi

Danyal Imani

Mahmood Jeddi-Tehrani

Mohammad Mehdi Amiri

Fazel Shokri

Affiliations

Soon will be listed here.

Abstract

Background: Waning immunity and emergence of new variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), highlight the need for further research in vaccine development.

Methods: A recombinant fusion protein containing the receptor-binding domain (RBD) fused to the human IgG1 Fc (RBD-Fc) was produced in CHO-K1 cells. RBD-Fc was emulsified with four adjuvants to evaluate its immunogenicity. The RBD-specific humoral and cellular immune responses were assessed by ELISA. The virus neutralizing potency of the vaccine was investigated using four neutralization methods. Safety was studied in mice and rabbits, and Antibody-Dependent Enhancement (ADE) effects were investigated by flow cytometry.

Results: RBD-Fc emulsified in Alum induced a high titer of anti-RBD antibodies with remarkable efficacy in neutralizing both pseudotyped and live SARS-CoV-2 Delta variant. The neutralization potency dropped significantly in response to the Omicron variant. RBD-Fc induced both TH2 and particularly TH1 immune responses. Histopathologic examinations demonstrated no substantial pathologic changes in different organs. No changes in serum biochemical and hematologic parameters were observed. ADE effect was not observed following immunization with RBD-Fc.

Conclusion: RBD-Fc elicits highly robust neutralizing antibodies and cellular immune responses, with no adverse effects. Therefore, it could be considered a promising and safe subunit vaccine against SARS-CoV-2.

Citing Articles

Quality by design for transient RBD-Fc fusion protein production in Chinese hamster ovary cells.

Jivapetthai A, Arunmanee W, Pornputtapong N Biotechnol Rep (Amst). 2025; 45:e00882.

PMID: 40034964 PMC: 11872631. DOI: 10.1016/j.btre.2025.e00882.

Fusion protein-based COVID-19 vaccines exemplified by a chimeric vaccine based on a single fusion protein (W-PreS-O).

Gattinger P, Kozlovskaya L, Lunin A, Gancharova O, Sirazova D, Apolokhov V Front Immunol. 2025; 16:1452814.

PMID: 39935478 PMC: 11811753. DOI: 10.3389/fimmu.2025.1452814.

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