Recombinant SARS-CoV-2 RBD with a built in T helper epitope induces strong neutralization antibody response

Area of Science:

• Immunology
• Virology
• Vaccine Development

Background:

• The COVID-19 pandemic necessitates urgent development of effective vaccines.
• Current treatment options for SARS-CoV-2 are limited, with no approved vaccines available.

Purpose of the Study:

• To evaluate a novel recombinant protein (S1-4) derived from the SARS-CoV-2 spike protein as a potential vaccine candidate.
• To assess the antigenicity, immunogenicity, and preliminary protective efficacy of the S1-4 protein.

Main Methods:

• Expression and purification of SARS-CoV-2 spike protein fragments (S1-4 and S1-5).
• Evaluation of antigenicity via Western Blotting (WB).
• Assessment of immunogenicity and cellular immunity in mice, with preliminary protective efficiency measured by microneutralization assay (MN50).

Main Results:

• The S1-4 protein, adjuvanted with Alum, induced a robust antibody response and significant Th2-type cellular immunity, supplemented by Th1-type immunity in mice.
• Immune sera from S1-4 immunized mice demonstrated neutralizing activity against SARS-CoV-2, protecting Vero E6 cells with a titer of 256.
• The recombinant protein elicited both humoral and cellular immune responses, indicating its potential as a subunit vaccine.

Conclusions:

• Recombinant SARS-CoV-2 spike protein fragment S1-4, incorporating a T helper epitope, is a promising candidate for a subunit vaccine.
• The S1-4 protein effectively stimulates both humoral and cellular immunity in a mouse model.
• Further development of S1-4 could lead to a viable vaccine against SARS-CoV-2.