Development of a peptide-based vaccine using a T cell epitope derived from SARS-CoV-2

Follicular helper T (Tfh) cells are a subset of CD4⁺ T cells that help B cells to produce high-affinity antibodies. Efficient Tfh cell induction by vaccines is critical for protective efficacy against diseases. A Tfh epitope, identified from the SARS-CoV-2 spike protein, has been shown to bind to the corresponding HLA and activates Tfh cells. Here, we assessed the efficacy of a peptide vaccine conjugated with SARS-CoV-2 Tfh epitope against experimental hypertension in a mouse model. The Tfh-angiotensin II (Tfh-Ang II) vaccine activated Tfh and germinal center B cells and induced antibodies against Ang II, thereby suppressing hypertension. However, Ang II-specific autoreactive T cells were not induced. Interestingly, Tfh-Ang II-induced antibody production was enhanced by SARS-CoV-2 spike priming. Moreover, human peripheral blood mononuclear cells from individuals vaccinated with COVID-19 mRNA vaccine were activated by Tfh epitope. Collectively, the SARS-CoV-2 spike-derived universal Tfh epitope may be effective for peptide-based vaccine development.