Early immune responses in the lung and blood following a randomized controlled human inhaled infection with aerosolized attenuated Mycobacterium Bovis BCG in healthy, BCG-naïve, UK adults

We utilise an aerosol mycobacterial human challenge model using attenuated M.bovis BCG, in BCG-naïve UK adult volunteers, to define the initial innate and adaptive immune events at the airway parenchymal interface, and in the blood. Blinded volunteers were randomised to inhale 1x10^7 CFU aerosolised BCG Danish or 0.9% saline (20:6); and sequentially allocated to bronchoscopy at day 2 or 7 post-inhalation (10 BCG, 3 saline each timepoint). scRNA-seq was conducted using the Bronchoalveolar lavage (BAL) samples collected 2 days and 7 days post-aerosol BCG infection and from the saline controls. Three BAL samples were collected from three volunteers 2 days post-aerosol BCG infection, three BAL samples were collected from another three volunteers 7 days post-aerosol BCG infection. Three BAL samples were collected from three volunteers 2 days post saline inhalation, three BAL samples were collected from another three volunteers 7 days post saline inhalation.