== Social Demographic Characteristics. LLoQ, lower limit of quantification; Visit 1, preRSV-season visit; Visit 2, visit when RSV-ARTI was reported; and Visit 2c, convalescence visit about 2 weeks after reporting RSV-ARTI. == Physique1. more predictive than functional antibody data LAMB3 (area under receiver operating characteristic curve [AUROC] for the models were 99% and 76%, respectively). The pre-RSV season T-cell phenotypes which were selected by the ML modelling and which were more frequent in RSV-Asymptomatic group than in the RSV-ARTI group, coincided with prominent phenotypes recognized during convalescence from RSV-ARTI (e.g., IFN-+, TNF-+ and CD40L+ for CD4+, and IFN-+ and 4-1BB+ for CD8+). == Conclusion == The evaluation and statistical modelling of numerous immunological parameters over the RSV season suggests a primary role of cellular immunity in preventing symptomatic RSV infections in older adults. Keywords:respiratory syncytial computer virus, cell-mediated immunity, correlate of protection, interferon-gamma, T-cell memory, CD4+ T cell, antibody function, machine learning == 1. Introduction == In older adults, respiratory syncytial computer virus (RSV) infections typically give rise to mild upper respiratory coryzal symptoms but can Deltasonamide 2 lead to severe or life-threatening pneumonia (15). Previous Deltasonamide 2 infections provide partial protection from reinfection and disease (6), but this immunity is usually transient (7). The RESCEU older-adults prospective-cohort study was designed to further understand the relationship between natural immunity and the epidemiology of RSV in older adults. A thousand participants aged at least 60 years were recruited in Northern Europe and followed over an RSV season between 2017 and 2019, and provided samples of peripheral-blood and nasopharyngeal swabs (8). The RSV contamination rate was estimated at 4.2 and 7.2% during the 2017-2018 and 2018-2019 RSV-seasons, respectively (9). The analyses reported thus far by RESCEU found an association between the susceptibility to RSV acute respiratory tract contamination (RSV-ARTI) and levels of certain types of antibodies (ner DRESCEU investigators, 20231). We have shown that susceptibility to RSV-ARTI is related to: (i) the preRSV-season serum level of pre-Fspecific IgGs; (ii) the preRSV-season mucosal level of pre-Fspecific IgAs (but not IgGs); and (iii) the Deltasonamide 2 preRSV-season serum level of RSV G-proteinspecific IgGs. By contrast, no associations were found between symptomatic and Deltasonamide 2 asymptomatic infections and levels of RSV-specific antibodies, including neutralizing antibodies (ner DRESCEU investigators, 20231). Elsewhere, other recent studies have identified functional features in antibodies beyond neutralization that protect against RSV-challenge; including features reinforced by vaccination (10,11). The potential importance of T-cell responses has also been highlighted by RSV-challenge studies (6,1214), which show enhanced susceptibility to RSV-ARTI with age and an associated with a decline in RSV F-specific IFN-producing T cells in peripheral blood. However, it is not known to what extent T-cell recognition contributes to defense against natural symptomatic contamination. The three objectives of this study were (i) to identify associations between RSV-ARTI and T-cell responses to RSV, (ii) to identify if the susceptibility to RSV-ARTI can be predicted by T-cell or functional antibody data prior to the RSV-season; and (iii) to assess whether combining T-cell data with functional antibody data would improve predicting susceptibility to RSV-ARTI. == 2. Materials and methods == == 2.1. Study design and demographics == The samples were obtained from the RESCEU older adult study (ClinicalTrials.gov:NCT03621930), which was a multi-country, multi-center, longitudinal, prospective, and observational cohort study (8, ner DRESCEU investigators, 20231). Overall, 1040 community-dwelling adults aged over 60 years were recruited before the 2017-2018 or 2018-2019 RSV season (1st of October to 1st May) and followed during the subsequent season. The individuals were from the general community in The Netherlands, Belgium, and the United Kingdom. The median age was 75 years and 54% were female, and there were no remarkable differences in the demographic characteristics between participants who experienced RSV-ARTI and those who did not (median ages were75.5 and 76.0 years, respectively (8, ner DRESCEU investigators, 20231). In the present study, two groups of individuals were analyzed and were recognized from within the entire RESCEU older adult.