Front Immunol . A Highly Conserved Peptide Vaccine Candidate Activates Both Humoral and Cellular Immunity Against SARS-CoV-2 Variant Strains

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Front Immunol


. 2021 Dec 7;12:789905.
doi: 10.3389/fimmu.2021.789905. eCollection 2021.
A Highly Conserved Peptide Vaccine Candidate Activates Both Humoral and Cellular Immunity Against SARS-CoV-2 Variant Strains


Fengxia Gao ^{1 2} , Jingjing Huang ^{1 2} , Tingting Li ^{1 2} , Chao Hu ^{1 2} , Meiying Shen ³ , Song Mu ^{1 2} , Feiyang Luo ^{1 2} , Shuyi Song ^{1 2} , Yanan Hao ^{1 2} , Wang Wang ^{1 2} , Xiaojian Han ^{1 2} , Chen Qian ^{1 2} , Yingming Wang ^{1 2} , Ruixin Wu ^{1 2} , Luo Li ^{1 2} , Shenglong Li ^{1 2} , Aishun Jin ^{1 2}



Affiliations

• PMID: 34950151
• PMCID: PMC8688401
• DOI: 10.3389/fimmu.2021.789905

Abstract

Facing the imminent need for vaccine candidates with cross-protection against globally circulating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mutants, we present a conserved antigenic peptide RBD9.1 with both T-cell and B-cell epitopes. RBD9.1 can be recognized by coronavirus disease 2019 (COVID-19) convalescent serum, particularly for those with high neutralizing potency. Immunization with RBD9.1 can successfully induce the production of the receptor-binding domain (RBD)-specific antibodies in Balb/c mice. Importantly, the immunized sera exhibit sustained neutralizing efficacy against multiple dominant SARS-CoV-2 variant strains, including B.1.617.2 that carries a point mutation (S^L452R) within the sequence of RBD9.1. Specifically, S^Y451 and S^Y454 are identified as the key amino acids for the binding of the induced RBD-specific antibodies to RBD9.1. Furthermore, we have confirmed that the RBD9.1 antigenic peptide can induce a S^448-456 (NYNYLYRLF)-specific CD8⁺ T-cell response. Both RBD9.1-specific B cells and the S^448-456-specific T cells can still be activated more than 3 months post the last immunization. This study provides a potential vaccine candidate that can generate long-term protective efficacy over SARS-CoV-2 variants, with the unique functional mechanism of activating both humoral and cellular immunity.

Keywords: RBD9.1; SARS-CoV-2 variants; cellular immune response; humoral immune response; immunological memory; vaccine.