title: Brucella melitensis invades murine erythrocytes during infection.
abstract: Brucella spp. are facultative intracellular Gram-negative coccobacilli responsible for brucellosis, a worldwide zoonosis. We observed that Brucella melitensis is able to persist for several weeks in the blood of intraperitoneally infected mice and that transferred blood at any time point tested is able to induce infection in naive recipient mice. Bacterial persistence in the blood is dramatically impaired by specific antibodies induced following Brucella vaccination. In contrast to Bartonella, the type IV secretion system and flagellar expression are not critically required for the persistence of Brucella in blood. ImageStream analysis of blood cells showed that following a brief extracellular phase, Brucella is associated mainly with the erythrocytes. Examination by confocal microscopy and transmission electron microscopy formally demonstrated that B. melitensis is able to invade erythrocytes in vivo. The bacteria do not seem to multiply in erythrocytes and are found free in the cytoplasm. Our results open up new areas for investigation and should serve in the development of novel strategies for the treatment or prophylaxis of brucellosis. Invasion of erythrocytes could potentially protect the bacterial cells from the host's immune response and hamper antibiotic treatment and suggests possible Brucella transmission by bloodsucking insects in nature.
authors.affiliation: Unité de Recherche en Biologie des Microorganismes, Laboratoire d'Immunologie et de Microbiologie, NARILIS, University of Namur (UNamur), Namur, Belgium.
authors.forename: Marie-Alice
authors.initials: MA
authors.lastname: Vitry
authors.affiliation: Unité de Recherche en Biologie des Microorganismes, Laboratoire d'Immunologie et de Microbiologie, NARILIS, University of Namur (UNamur), Namur, Belgium.
authors.forename: Delphine
authors.initials: D
authors.lastname: Hanot Mambres
authors.affiliation: Unité de Recherche en Biologie des Microorganismes, Laboratoire d'Immunologie et de Microbiologie, NARILIS, University of Namur (UNamur), Namur, Belgium.
authors.forename: Michaël
authors.initials: M
authors.lastname: Deghelt
authors.affiliation: Unité de Recherche en Biologie des Microorganismes, Laboratoire d'Immunologie et de Microbiologie, NARILIS, University of Namur (UNamur), Namur, Belgium.
authors.forename: Katrin
authors.initials: K
authors.lastname: Hack
authors.affiliation: Unité de Recherche en Biologie des Microorganismes, Laboratoire d'Immunologie et de Microbiologie, NARILIS, University of Namur (UNamur), Namur, Belgium.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Machelart
authors.affiliation: Center for Microscopy and Molecular Imaging, Université Libre de Bruxelles (ULB), Gosselies, Belgium.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Lhomme
authors.affiliation: Laboratory of Neurophysiology, ULB, Campus Erasme, Brussels, Belgium.
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Vanderwinden
authors.affiliation: Center for Microscopy and Molecular Imaging, Université Libre de Bruxelles (ULB), Gosselies, Belgium.
authors.forename: Marjorie
authors.initials: M
authors.lastname: Vermeersch
authors.affiliation: Department of Molecular and Cellular Interactions, Vlaams Interuniversitair Instituut voor Biotechnologie, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Carl
authors.initials: C
authors.lastname: De Trez
authors.affiliation: Unité de Recherche en Biologie des Microorganismes, Laboratoire d'Immunologie et de Microbiologie, NARILIS, University of Namur (UNamur), Namur, Belgium Center for Microscopy and Molecular Imaging, Université Libre de Bruxelles (ULB), Gosselies, Belgium.
authors.forename: David
authors.initials: D
authors.lastname: Pérez-Morga
authors.affiliation: Unité de Recherche en Biologie des Microorganismes, Laboratoire d'Immunologie et de Microbiologie, NARILIS, University of Namur (UNamur), Namur, Belgium.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Letesson
authors.affiliation: Unité de Recherche en Biologie des Microorganismes, Laboratoire d'Immunologie et de Microbiologie, NARILIS, University of Namur (UNamur), Namur, Belgium Laboratoire de Parasitologie, Faculté de Médecine, ULB, Brussels, Belgium emuraille@hotmail.com.
authors.forename: Eric
authors.initials: E
authors.lastname: Muraille
mesh_terms: D000818:Animals; D058947:Bacterial Secretion Systems / Q000276:immunology; D002004:Brucella Vaccine / Q000276:immunology; D017347:Brucella melitensis / Q000276:immunology*; D002006:Brucellosis / Q000276:immunology / Q000382:microbiology; D004912:Erythrocytes / Q000276:immunology* / Q000382:microbiology; D005407:Flagella / Q000276:immunology / Q000382:microbiology; D051379:Mice; D008810:Mice, Inbred C57BL
chemical_list: D058947:Bacterial Secretion Systems; D002004:Brucella Vaccine