title: Bloodstream- versus tick-associated variants of a relapsing fever bacterium.
abstract: The relapsing fever spirochete, Borrelia hermsii, alternates infections between a mammal and a tick vector. Whether the spirochete changes phenotypically in the different hosts was examined by allowing the tick vector Ornithodoros hermsi to feed on mice infected with serotype 7 or serotype 8 of B. hermsii. Upon infection of ticks, the spirochetal serotype-specific variable major proteins (Vmps) 7 and 8 became undetectable and were replaced by Vmp33. This switch from a bloodstream- to tick-associated phenotype could be induced in culture by a decrease in temperature. After tick-bite transmission back to mice, the process was reversed and the spirochetes resumed expression of the same Vmp present in the previous infectious blood meal.
authors.affiliation: Laboratory of Microbial Structure and Function, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA. tom_schwn@nih.gov
authors.forename: T G
authors.initials: TG
authors.lastname: Schwan
authors.forename: B J
authors.initials: BJ
authors.lastname: Hinnebusch
mesh_terms: D000818:Animals; D000940:Antigenic Variation; D000942:Antigens, Bacterial / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D000954:Antigens, Surface / Q000032:analysis / Q000235:genetics / Q000276:immunology; D001096:Arachnid Vectors / Q000382:microbiology; D016470:Bacteremia / Q000382:microbiology; D001425:Bacterial Outer Membrane Proteins / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D001898:Borrelia / Q000145:classification / Q000235:genetics* / Q000276:immunology; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D005798:Genes, Bacterial; D051379:Mice; D008807:Mice, Inbred BALB C; D012061:Relapsing Fever / Q000382:microbiology* / Q000635:transmission; D012469:Salivary Glands / Q000382:microbiology; D012703:Serotyping; D013987:Ticks / Q000382:microbiology*
chemical_list: D000942:Antigens, Bacterial; D000954:Antigens, Surface; D001425:Bacterial Outer Membrane Proteins; C079616:OspC protein; C067934:VMP7 protein, Borrelia hermsii