title: A bovine model of a respiratory Parachlamydia acanthamoebae infection.
abstract: The aim of this study was to evaluate the pathogenicity of Parachlamydia (P.) acanthamoebae as a potential agent of lower respiratory tract disease in a bovine model of induced lung infection. Intrabronchial inoculation with P. acanthamoebae was performed in healthy calves aged 2-3 months using two challenge doses: 10(8) and 10(10) bacteria per animal. Controls received 10(8) heat-inactivated bacteria. Challenge with 10(8) viable Parachlamydia resulted in a mild degree of general indisposition, whereas 10(10) bacteria induced a more severe respiratory illness becoming apparent 1-2 days post inoculation (dpi), affecting 9/9 (100%) animals and lasting for 6 days. The extent of macroscopic pulmonary lesions was as high as 6.6 (6.0)% [median (range)] of lung tissue at 2-4 dpi and correlated with parachlamydial genomic copy numbers detected by PCR, and with bacterial load estimated by immunohistochemistry in lung tissue. Clinical outcome, acute phase reactants, pathological findings and bacterial load exhibited an initial dose-dependent effect on severity. Animals fully recovered from clinical signs of respiratory disease within 5 days. The bovine lung was shown to be moderately susceptible to P. acanthamoebae, exhibiting a transient pneumonic inflammation after intrabronchial challenge. Further studies are warranted to determine the precise pathophysiologic pathways of host-pathogen interaction.
authors.affiliation: Institute of Molecular Pathogenesis at Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Jena, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Lohr
authors.affiliation: Institute of Molecular Pathogenesis at Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Jena, Germany.
authors.forename: Annette
authors.initials: A
authors.lastname: Prohl
authors.affiliation: Institute of Molecular Pathogenesis at Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Jena, Germany.
authors.forename: Carola
authors.initials: C
authors.lastname: Ostermann
authors.affiliation: Institute of Molecular Pathogenesis at Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Jena, Germany.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Liebler-Tenorio
authors.affiliation: Institute of Bacteriology and Mycology, Faculty of Veterinary Medicine, University of Leipzig, Leipzig, Germany.
authors.forename: Wieland
authors.initials: W
authors.lastname: Schroedl
authors.affiliation: Center for Research on Intracellular Bacteria, Institute of Microbiology, University Hospital Center and University of Lausanne, Lausanne, Switzerland.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Aeby
authors.affiliation: Center for Research on Intracellular Bacteria, Institute of Microbiology, University Hospital Center and University of Lausanne, Lausanne, Switzerland.
authors.forename: Gilbert
authors.initials: G
authors.lastname: Greub
authors.affiliation: Institute of Molecular Pathogenesis at Friedrich-Loeffler-Institut (Federal Research Institute for Animal Health), Jena, Germany petra.reinhold@fli.bund.de.
authors.forename: Petra
authors.initials: P
authors.lastname: Reinhold
mesh_terms: D000818:Animals; D058491:Bacterial Load; D002417:Cattle; D002695:Chlamydiales / Q000254:growth & development / Q000302:isolation & purification*; D004195:Disease Models, Animal; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology* / Q000473:pathology*; D007150:Immunohistochemistry; D008168:Lung / Q000473:pathology; D008297:Male; D018410:Pneumonia, Bacterial / Q000382:microbiology* / Q000473:pathology*; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D012720:Severity of Illness Index
keywords: Chlamydia-like organism; Parachlamydia; large animal model; pneumonia