{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T05:02:13Z","timestamp":1784869333521,"version":"3.55.0"},"reference-count":70,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T00:00:00Z","timestamp":1784851200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Immunol."],"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Vaccines against SARS-CoV-2 and influenza require reformulation due to viral evolution. It remains unclear how vaccination against evolving antigens influences T-cell responses and the impact of reformulation on T-cell responses to new variants in immunocompromised hosts. Solid organ transplant recipients (SOTRs) had significantly lower antibody levels following vaccination and required repeated boosting during the COVID-19 pandemic.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>With the introduction of the Omicron spike (S) to the bivalent mRNA vaccines in 2022, the relative contribution of T-cell responses cross-reactive for Omicron mutated S sequences was assessed via intracellular cytokine staining using peptide pools containing conserved or mutated S sequences.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>S-specific CD4 T cells recognize both conserved and Omicron mutated S sequences pre- and post-bivalent vaccination, even in the absence of evidence of prior infection as detected by T-cell responses to a novel peptide pool. CD4 T-cell responses to both conserved and Omicron mutated sequences correlated with antibody pseudo-neutralization of BA.5 S. Importantly, pre-bivalent conserved S CD4 T-cell responses significantly correlated with antibody pseudo-neutralization of BA.5 S post-bivalent.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Discussion<\/jats:title>\n                    <jats:p>These results emphasize the importance of conserved and cross-reactive responses in vaccine immunogenicity, providing a mechanism through which repeated boosting enhances vaccine immunogenicity in SOTRs and other immunocompromised populations.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fimmu.2026.1856861","type":"journal-article","created":{"date-parts":[[2026,7,24]],"date-time":"2026-07-24T04:24:38Z","timestamp":1784867078000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Conserved CD4 T-cell responses correlate with antibody neutralization in solid organ transplant recipients after bivalent SARS-CoV-2 vaccination"],"prefix":"10.3389","volume":"17","author":[{"given":"Georgia","family":"Stavrakis","sequence":"first","affiliation":[{"name":"Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health","place":["Baltimore, MD, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Katerina","family":"Roznik","sequence":"additional","affiliation":[{"name":"Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health","place":["Baltimore, MD, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Laila","family":"Stoddart","sequence":"additional","affiliation":[{"name":"Department of Medicine, Johns Hopkins University School of Medicine","place":["Baltimore, MD, United States"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"T. 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