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Vaccines and Immunoinformatics Approaches / Respiratory Viral Infections Research · Journal article
The Journal of Immunology · July 28, 2026
Encouraging direction, but not yet definitive.
This preclinical study demonstrates that total respiratory tract (TRT) boosting after intramuscular priming induces higher spike-specific CD4+ and CD8+ T cells and resident memory cells in murine lungs compared to upper respiratory tract (URT) or IM boosting alone, and is the only strategy generating both serum and lung spike-specific IgA. The findings identify epitope-driven CD4+ T cell differentiation as a mechanistic driver of immune response quality, suggesting a rational approach to respiratory vaccine optimization in animal models.
Preclinical controlled comparison of boost strategies in mice. Laboratory mice (specific strain not stated) receiving SARS-CoV-2 spike protein immunization. Intervention: Total respiratory tract (TRT) boosting via intranasal vaccination following IM priming. Compared with: Upper respiratory tract (URT) intranasal boosting or intramuscular (IM) boosting following the same IM prime.
TRT boosting increased spike-specific CD4+ and CD8+ T cell numbers in lungs at 4 weeks post-boost versus URT or IM TRT induced higher frequencies and numbers of CD4+ and CD8+ resident memory T cells (TRM) in lungs compared to URT or IM TRT was the only boost strategy that induced both serum and lung spike-specific IgA
No data on vaccine safety, tolerability, or adverse effects
These findings are mechanistically informative for respiratory vaccine design but remain preclinical. Translation to human respiratory vaccination strategies requires clinical validation; the superiority of TRT boosting in immune profiling does not yet establish clinical superiority in efficacy, safety, or tolerability.
A rigorous preclinical immunology study with sound design and clear mechanistic findings on vaccine-induced immune responses, but limited to mouse models without clinical efficacy data in humans.
As stated by the source record.
Quoted from the source exactly as published.
These findings are mechanistically informative for respiratory vaccine design but remain preclinical. Translation to human respiratory vaccination strategies requires clinical validation; the superiority of TRT boosting in immune profiling does not yet establish clinical superiority in efficacy, safety, or tolerability.
Graded across the dimensions that decide whether you should act, each from what the source actually supports. There is no single score, and where a dimension was not assessed it says so.
Abstract Introduction Respiratory infections represent a major global health challenge. Different intranasal vaccine strategies can target specific areas of the respiratory tract, which may influence local and systemic immune responses. Methods Here, we combined peptide-major histocompatibility complex class I and II (pMHCI and pMHCII) tetramers with flow cytometry and single cell RNA sequencing (scRNAseq) to comprehensively study spike-specific CD8+ and CD4+ T cells following immunization with SARS-CoV2 spike protein. Following intramuscular (IM) priming with spike protein and poly:IC, we compared different boosting strategies - upper respiratory tract (URT), total respiratory tract (TRT), and IM. Results At 4 weeks post-boost, the number of spike-specific CD4+ and CD8+ T cells was higher in the lungs of mice receiving TRT boosting compared to URT or IM boosting. We also observed higher frequencies and numbers of CD4+ and CD8+ resident memory T cells (TRM) in the lungs of TRT versus URT or IM groups. In the nasal mucosa (NM), both TRT and URT boosting resulted in higher frequencies of spike-specific CD4+ and CD8+ TRM cells than IM. Notably, TRT was the only boost strategy that induced serum and lung spike-specific IgA. However, despite generating fewer spike-specific T cells and antibodies than TRT, URT boosting still protected mice against viral challenge. Moreover, both spike-specific CD4+ and CD8+ T cells obtained from the NM expressed higher levels of IFN-g, and spike-specific CD8+ T cells in the NM produced higher levels of granzyme B compared to those cells recovered from lung and spleen. Finally, scRNAseq analysis with barcoded tetramers revealed that epitope specificity influenced CD4+ T cell differentiation resulting in epitope-specific T helper cell bias. Conclusion In sum, TRT boosting enhanced lung immunity and epitope-driven CD4+ T cell phenotypes offer a promising approach to guide optimized vaccine design. Funding Source NIH P01 AI165072 AND AMERICAN LUNG ASSOCIATION CA-1252074 Topic Categories Mucosal and Regional Immunology (MUC)
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