title: Gene conversion: a mechanism for generation of heterogeneity in the tprK gene of Treponema pallidum during infection.
abstract: The tprK gene sequence of Treponema pallidum subspecies pallidum (T. pallidum) is heterogeneous within and among isolates. Heterogeneity in the tprK open reading frame is localized in seven discrete variable (V) regions, and variability results from apparent base changes, insertions or deletions. The TprK V regions are the focus of anti-TprK antibodies arising during infection. To test our hypothesis that V region sequences change during infection and passage, we developed a clonal isolate from the Chicago strain of T. pallidum and confirmed V region diversification during passage of this isolate. We describe the sequence anatomy of the seven V regions of tprK and the identification of putative donor sites for new V region sequences, and we propose a model for generation of new V regions by segmental gene conversion. These findings suggest that antigenic variation of TprK occurs in T. pallidum and may be important in immune evasion and persistence.
authors.affiliation: Department of Medicine, University of Washington, Harborview Medical Center, Box 359779, 325 Ninth Ave., Seattle, WA 98104, USA. acentur@u.washington.edu
authors.forename: Arturo
authors.initials: A
authors.lastname: Centurion-Lara
authors.forename: Rebecca E
authors.initials: RE
authors.lastname: LaFond
authors.forename: Karin
authors.initials: K
authors.lastname: Hevner
authors.forename: Charmie
authors.initials: C
authors.lastname: Godornes
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Molini
authors.forename: Wesley C
authors.initials: WC
authors.lastname: Van Voorhis
authors.forename: Sheila A
authors.initials: SA
authors.lastname: Lukehart
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000940:Antigenic Variation; D000954:Antigens, Surface / Q000235:genetics / Q000276:immunology; D001426:Bacterial Proteins / Q000235:genetics* / Q000276:immunology*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D005785:Gene Conversion; D005798:Genes, Bacterial; D014644:Genetic Variation; D008297:Male; D008969:Molecular Sequence Data; D018272:Porins / Q000235:genetics* / Q000276:immunology*; D011817:Rabbits; D017422:Sequence Analysis, DNA; D013587:Syphilis / Q000382:microbiology*; D013737:Testis / Q000382:microbiology; D014210:Treponema pallidum / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity
chemical_list: D000954:Antigens, Surface; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D018272:Porins; C099361:major outer sheath protein, Treponema