title: A nose-only apparatus for airborne delivery of Mycobacterium tuberculosis to mice: calibration of biological parameters.
abstract: Mycobacterium tuberculosis is the main cause of tuberculosis and is still a public health concern worldwide. This mycobacterium is transmitted through aerosols from human beings suffering from pulmonary tuberculosis to susceptible persons. To study this natural route of infection, we designed a new nose-only aerosol apparatus--system of aerosolisation of microorganisms (SAM)--in a carefully designed biohazard facility. For safety reasons, Mycobacterium smegmatis was first used to calibrate several parameters, such as inoculum density, atmospheric conditions (i.e. hygrometry) and particle size distribution. We present evidence that our apparatus is totally adapted to airborne delivery; the particle size of generated aerosol ranges from 1 to 7 microm, which is ideal for an infection by inhalation. We found that 99% of generated particles (<7 microm) could be retained by the respiratory tract, and among these particles, 62-79% (<3.3 microm) were able to reach pulmonary compartments. The next step was to simultaneously challenge 48 mice with M. tuberculosis in a highly reproducible way. We showed that a moderate dose (4 log10 colony-forming units (CFU) per mice) of M. tuberculosis was capable of causing progressive lung pathology and death in mice 30 days post-aerosolisation. Therefore, our apparatus, once calibrated, is easy to handle, safe, and can be used with any pathogen, which is spread by aerosol.
authors.affiliation: Département d'analyse biologique, Centre d'études du Bouchet, BP3 91710 Vert-le-Petit, France. celine.louveau@dga.defense.gouv.fr
authors.forename: Céline
authors.initials: C
authors.lastname: Louveau
authors.forename: Damien
authors.initials: D
authors.lastname: Descroix
authors.forename: Laurence
authors.initials: L
authors.lastname: Garnier
authors.forename: Iroudayanadin
authors.initials: I
authors.lastname: Delamanche
authors.forename: Pierre
authors.initials: P
authors.lastname: Chavarot
authors.forename: Françoise
authors.initials: F
authors.lastname: Ramisse
authors.forename: Gilles
authors.initials: G
authors.lastname: Marchal
authors.forename: Gilles
authors.initials: G
authors.lastname: Vergnaud
mesh_terms: D000336:Aerosols; D000818:Animals; D003264:Containment of Biohazards; D004195:Disease Models, Animal; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D009169:Mycobacterium tuberculosis; D009330:Nebulizers and Vaporizers; D010316:Particle Size; D014397:Tuberculosis, Pulmonary / Q000635:transmission
chemical_list: D000336:Aerosols