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Background: Chlamydia trachomatis (CT) is a globally prevalent sexually transmitted infection that can result in pelvic inflammatory disease, ectopic pregnancy, and infertility in women. Currently, there is no prophylactic vaccine., Methods: This study examined T-cell immunity in a cohort of women recently infected with CT. Participants were screened against peptides spanning 33 of 894 possible CT proteins, either ex vivo or using short-term cell lines. CT-specific T cells were characterized by interferon (IFN) γ enzyme-linked immunospot (ELISPOT) assay and flow cytometry., Results: Ex vivo CT-specific T cells were rarely detected; however, in vitro expanded CT-specific T cells were detected by IFN-γ ELISPOT in 90% (27 of 30) of participants. Notably, >50% of participants had T-cell responses targeting chlamydial proteaselike activity factor (CPAF). T-cell epitopes were dispersed across the CPAF protein. Flow cytometric analysis of short-term cell lines found that CT-specific cells, mainly CD4, produced IFN-γ and tumor necrosis factor (TNF) α and were sustained over 12 months. Ex vivo analysis suggested that CT-specific T cells mostly exhibited a central memory phenotype., Conclusions: Our results indicate that CT infection elicits low-frequency, persistent CD4 T-cell responses in most women and that the secreted protein, CPAF, is an immunoprevalent CT antigen. Altogether, these data support development and testing of CT vaccines that enhance CD4 T cells against CPAF., Competing Interests: Potential conflicts of interest . All authors: No reported conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2024. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)

Introduction: Risk stratification for CMV infection in lung transplantation (LT) currently relies on determining donor and recipient CMV IgG before transplantation. However, it has been observed that some patients who test positive for CMV-specific humoral response before kidney transplantation (KT) exhibit a weak or absent CMV-specific cellular response. The significance of this observation in LT is still unknown., Methods: This prospective, multicenter, observational study evaluated the agreement between CMV IgG serology and specific cell-mediated response (specific T cell Enzyme-Linked ImmunoSpot Assay, ELISPOT, against CMV pp65 and IE-1 antigens) in 121 patients on the waiting list for LT., Results: One hundred and four (86%) patients were seropositive for CMV. Discordant humoral and cellular immunologic responses were observed, 29% of seropositive patients had a weak ELISPOT response to IE-1 and 39% to pp65. In 22% of seropositive patients, there was a weak or no response to both antigens. All seronegative patients did not respond to either antigen., Conclusions: Therefore, over 20% of CMV seropositive LT candidates showed weak CMV-specific cellular immune responses despite detectable serological memory against CMV. This may be important in assessing the risk of developing a CMV infection after transplantation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision. The authors declare that this study received funding from Merck Sharp & Dohme (MSD) Spain. The funder had the following involvement in the study: study design, study analysis, data interpretation and decision to publish., (Copyright © 2025 Boada-Pérez, Berastegui, Erro, Ussetti, Crespo, Donadeu, Bestard, Anguera, Solé, Ponz Mir, Molloy, Revilla-López, Monforte and Gómez-Ollés.)