Vaccine Candidate Against COVID-19 Based on Structurally Modified Plant Virus as an Adjuvant

Area of Science:

• Virology
• Immunology
• Vaccine Development

Background:

• Coronaviruses, including SARS-CoV-2, pose significant global health threats.
• Developing effective and broadly applicable vaccine strategies remains a priority.
• Novel adjuvants are crucial for enhancing vaccine immunogenicity and efficacy.

Purpose of the Study:

• To develop a recombinant vaccine candidate targeting major coronaviruses using S protein fragments.
• To evaluate the role of a novel adjuvant, spherical particles (SPs), in enhancing immune responses.
• To assess the immunogenicity and neutralizing activity of the developed vaccine candidate.

Main Methods:

• Recombinant antigens were designed using receptor-binding domains and conserved fragments of the S2 subunit of coronavirus spike proteins.
• A vaccine candidate (SPs + 3AG) was formulated with three antigens (Co1, CoF, PE) and SPs.
• Immunogenicity was tested in a mouse model, and neutralizing activity against SARS-CoV-2 was assessed in hamsters.

Main Results:

• The SPs + 3AG composition was recognized by antibodies against SARS-CoV and SARS-CoV-2 spike proteins.
• SPs significantly improved the immune response to CoF and PE antigens in mice, increasing IgG titers 9-16 fold.
• Serum from immunized hamsters demonstrated neutralizing activity against SARS-CoV-2.

Conclusions:

• The developed recombinant vaccine candidate (SPs + 3AG) shows potential for inducing robust immune responses.
• The novel SP adjuvant enhances the immunogenicity of coronavirus antigens.
• The vaccine candidate exhibits neutralizing activity against SARS-CoV-2, warranting further investigation.