T-cell responses to highly conserved SARS-CoV-2 epitopes in Hispanic Americans receiving an mRNA COVID-19 vaccine

• Published in: Human vaccines & immunotherapeutics Vol. 21; no. 1; p. 2501844
• Main Authors: Haltaufderhyde, Kirk, Gutiérrez, Andres H., McAllister, Mitchell, Boyle, Christine M., Moise, Leonard, Martin, William, De Groot, Anne S.
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 01.12.2025; Taylor & Francis Group
• Subjects: Adult; Brief Report; CoVID-19; COVID-19 - immunology; COVID-19 - prevention & control; COVID-19 Vaccines - administration & dosage; COVID-19 Vaccines - immunology; EpiMatrix; Epitopes, T-Lymphocyte - immunology; Female; Hispanic or Latino; Humans; Male; Middle Aged; mRNA Vaccines - immunology; Novel Vaccines; peptide; SARS-CoV-2; SARS-CoV-2 - immunology; Spike Glycoprotein, Coronavirus - genetics; Spike Glycoprotein, Coronavirus - immunology; T-cell epitope; T-Lymphocytes - immunology; vaccine; Vaccines, Synthetic - administration & dosage; Vaccines, Synthetic - immunology; SARS-CoV-2; peptide; vaccine; Latino; CoVID-19; T-cell epitope; EPV-CoV-19; EpiMatrix; conservatrix; Hispanic American
• ISSN: 2164-5515; 2164-554X; 2164-554X
• DOI: 10.1080/21645515.2025.2501844

This study reports the pre-clinical evaluation of peptides from EPV-CoV-19, a T cell epitope-based SARS-CoV-2 vaccine candidate, following spike-mRNA vaccination of a predominantly Hispanic American cohort. EPV-COV-19 peptides' potential to boost T cell responses to spike protein vaccines was evaluated, confirming previously observed memory recall responses in donors with prior immunity to COVID-19. The vaccinated subjects' averaged immune responses to the 15-peptide EPV-CoV-19 pool achieved 85% of the observed response to a spike protein peptide array containing a 7-fold greater epitope content, suggesting that the EPV-CoV-19 peptides have a higher relative concentration of T cell epitope content per-peptide. Ten of the 15 peptides contained spike epitopes conserved in the majority of variants of concern (VOC) evaluated over the 2020-2024 period. While commercial vaccines exhibited gradual loss of T cell epitope conservation with VOC over time, the EPV-CoV-19 epitope-peptides maintained conservation until the XBB variant emerged. The addition of one new peptide to the vaccine design reestablished broad T cell epitope coverage. These findings underscore the importance of identifying highly conserved T cell epitopes for vaccine designs that target rapidly-mutating strains of emergent pathogens, while also documenting broad memory T cell response to the vaccine in a predominantly Hispanic American cohort.