Development of a scalable single process for producing SARS-CoV-2 RBD monomer and dimer vaccine antigens

Area of Science:

• Biotechnology
• Vaccinology
• Protein Engineering

Background:

• The development of effective COVID-19 vaccines relies on high-quality antigens.
• The SARS-CoV-2 receptor binding domain (RBD) is a key target for neutralizing antibodies.
• Existing vaccine platforms utilize different forms of RBD, necessitating flexible production methods.

Purpose of the Study:

• To establish a single, scalable manufacturing process for both monomeric and dimeric SARS-CoV-2 RBD antigens.
• To characterize the quality attributes and immunogenicity of the produced RBD antigens.
• To demonstrate the adaptability of the process for future vaccine development against emerging variants.

Main Methods:

• Expression of RBD (319-541)-His6 in Chinese hamster ovary (CHO)-K1 cells.
• Optimization of culture conditions, including copper supplementation and perfusion culture.
• Purification using immobilized metal ion affinity chromatography (IMAC), ion exchange, and size exclusion chromatography.
• Comprehensive analysis of antigen structure, integrity, and in vitro interactions.

Main Results:

• A unified process successfully produced both monomeric and dimeric RBD antigens at laboratory and large scales (500 L).
• Copper supplementation was found to enhance IMAC performance for RBD purification.
• Extensive characterization confirmed the quality attributes, including structure, purity, and stability, of the produced antigens.
• Both RBD forms demonstrated ACE2 binding and immunogenicity in mice.

Conclusions:

• The developed process enables flexible, large-scale production of high-quality SARS-CoV-2 RBD antigens.
• This manufacturing approach supports rapid adaptation to new SARS-CoV-2 variants and diverse vaccine platforms.
• The characterized monomeric and dimeric RBD antigens meet the necessary criteria for COVID-19 vaccine production.