BAL bronchoalveolar lavage CF cystic fibrosis COPD chronic obstructive pulmonary disease FEV1 forced expiratory volume in 1 s Ig immunoglobulin IL interleukin LRT lower respiratory tract LRTI lower respiratory tract infection NGS next-generation sequencing rRNA ribosomal RNA RSV respiratory syncytial virus RTI respiratory tract infection TLR Toll-like receptor URT upper respiratory tract URTI upper respiratory tract infection List of abbreviations