title: An animal model of a newly emerging human ehrlichiosis.
abstract: BACKGROUND
  Human ehrlichioses are emerging life-threatening diseases transmitted by ticks. Animal models have been developed to study disease development; however, there is no valid small animal model that uses a human ehrlichial pathogen. The objective of this study was to develop a mouse model for ehrlichiosis with the newly discovered human pathogen, Ehrlichia muris-like agent (EMLA).
  
  
  METHODS
  Three strains of mice were inoculated with different doses of EMLA by the intravenous, intraperitoneal, or intradermal route and evaluated for clinical and pathologic changes during the course of infection.
  
  
  RESULTS
  EMLA infected C57Bl/6, BALB/c, and C3H/HeN mice and induced lethal or persistent infection in a route- and dose-dependent manner. The clinical chemistry and hematologic changes were similar to those of human infection by Ehrlichia chaffeensis or EMLA. Bacterial distribution in tissues differed after intradermal infection, compared with the distribution after intravenous or intraperitoneal injection. Lethal infection did not cause remarkable pathologic changes, but it caused fluid imbalance. EMLA infection of endothelium and mononuclear cells likely plays a role in the severe outcome.
  
  
  CONCLUSIONS
  The EMLA mouse model mimics human infection and can be used to study pathogenesis and immunity and for development of a vector transmission model of ehrlichiosis.
authors.affiliation: Department of Pathology, University of Texas Medical Branch at Galveston.
authors.forename: Tais Berelli
authors.initials: TB
authors.lastname: Saito
authors.affiliation: Department of Pathology, University of Texas Medical Branch at Galveston.
authors.forename: Nagaraja R
authors.initials: NR
authors.lastname: Thirumalapura
authors.affiliation: Department of Pathology, University of Texas Medical Branch at Galveston.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Shelite
authors.affiliation: Department of Pathology, University of Texas Medical Branch at Galveston.
authors.forename: Dedeke
authors.initials: D
authors.lastname: Rockx-Brouwer
authors.affiliation: Department of Pathology, University of Texas Medical Branch at Galveston.
authors.forename: Vsevolod L
authors.initials: VL
authors.lastname: Popov
authors.affiliation: Department of Pathology, University of Texas Medical Branch at Galveston.
authors.forename: David H
authors.initials: DH
authors.lastname: Walker
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D018469:Ehrlichia chaffeensis / Q000472:pathogenicity; D016873:Ehrlichiosis / Q000382:microbiology*; D005260:Female; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D013987:Ticks / Q000382:microbiology
keywords: Ehrlichia muris-like; ehrlichiosis; emerging infectious disease; human pathogen; tick-borne disease