Task 2.1 - Immune pathways (m1-36, BRFAA): 2.1.1: Direct effects of different phage preparations (from ELIBIO), on blood-derived macrophage and DC responses will be examined after in-vitro exposure in culture. 2.1.2: Leukocyte populations in nasopharyngeal brushings from subjects in WP1 will be characterized by multiparametric flow cytometry. Macrophages and DCs will be sorted and analysed by transcriptomics for the activation of immune sensing, antiviral and inflammatory pathways. Multiple cytokines and chemokines will be quantified in nasal lining fluid, using Luminex. Results will be associated with microbiome parameters from T3.2, used for composite phenotyping in T1.3 and for informing the model in T5.3.

Task 2.2 - Tissue integrity (m1-36, SIAF): 2.2.1: To examine the effects of bacteriophages on epithelial barrier integrity and tight junction molecules involved in controlling the process, we will use air-liquid interface (ALI) cultures. The effect of supernatants from these cultures on type 1, 2 &3 ILC will be determined. 2.2.2: Epithelial cells and ILCs will be sorted from nasopharyngeal brushings and PBMC of WP1 subjects respectively and analysed by transcriptomics for the activation of antiviral, inflammatory and tight junction-preserving pathways. Results will be used as in T3.1