Naive and Memory B Cell BCR Repertoires in Individuals Immunized with an Inactivated SARS-CoV-2 Vaccine

Area of Science:

• Immunology
• Vaccinology
• Molecular Biology

Background:

• The COVID-19 pandemic necessitated rapid vaccine development, including inactivated virus vaccines like CoronaVac.
• CoronaVac showed limitations against emerging SARS-CoV-2 variants.
• Memory B-cells are crucial for adaptive immunity and producing neutralizing antibodies.

Purpose of the Study:

• To investigate the B-cell memory repertoire following two doses of the CoronaVac vaccine.
• To understand the characteristics of antibodies generated by CoronaVac.

Main Methods:

• Isolation of memory B-cells from vaccinated and pre-pandemic individuals.
• In vitro stimulation of B-cells.
• High-throughput sequencing of the Heavy Chain Variable (VH) repertoire.

Main Results:

• A shift in the VH repertoire was observed, with increased HCDR3 length and specific VH gene enrichment for IgA and IgG B-cell receptors (BCRs).
• Significant expansion of IgA-specific clonal populations and shared IgA VH sequences were found in vaccinated individuals.
• Vaccinee antibody sequences showed convergence with known SARS-CoV-2 neutralizing antibodies.

Conclusions:

• CoronaVac elicits antibodies with characteristics of neutralizing antibodies, supporting its protective role.
• Immunization is vital for generating convergent antibodies, enhancing the antiviral immune response.