title: The lipoprotein La7 contributes to Borrelia burgdorferi persistence in ticks and their transmission to naïve hosts.
abstract: La7, an immunogenic outer membrane lipoprotein of Borrelia burgdorferi, produced during infection, has been shown to play a redundant role in mammalian infectivity. Here we show that La7 facilitates pathogen survival in all tested phases of the vector-specific spirochete life cycle, including tick-to-host transmission. Unlike wild type or la7-complemented isolates, isogenic La7-deficient spirochetes are severely impaired in their ability to persist within feeding ticks during acquisition from mice, in quiescent ticks during larval-nymphal inter-molt, and in subsequent pathogen transmission from ticks to naïve hosts. Analysis of gene expression during the major stages of the tick-rodent infection cycle showed increased expression of la7 in the vector and a swift downregulation in the mammalian hosts. Co-immunoprecipitation studies coupled with liquid chromatography-mass spectrometry analysis further suggested that La7, a highly conserved and abundant inner membrane protein, is involved in protein-protein interaction with a discrete set of borrelial ligands although biological significance of such interactions remains unclear. Further characterization of vector-induced membrane antigens like La7 and its interacting partners will likely aid in our understanding of the molecular details of B. burgdorferi persistence and transmission through a complex enzootic cycle.
authors.affiliation: Department of Veterinary Medicine, University of Maryland, College Park, MD 20742, USA; Virginia-Maryland Regional College of Veterinary Medicine, University of Maryland, College Park, MD 20742, USA.
authors.forename: Xiuli
authors.initials: X
authors.lastname: Yang
authors.forename: Shylaja
authors.initials: S
authors.lastname: Hegde
authors.forename: Deborah Y
authors.initials: DY
authors.lastname: Shroder
authors.forename: Alexis A
authors.initials: AA
authors.lastname: Smith
authors.forename: Kamoltip
authors.initials: K
authors.lastname: Promnares
authors.forename: Girish
authors.initials: G
authors.lastname: Neelakanta
authors.forename: John F
authors.initials: JF
authors.lastname: Anderson
authors.forename: Erol
authors.initials: E
authors.lastname: Fikrig
authors.forename: Utpal
authors.initials: U
authors.lastname: Pal
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D025065:Borrelia burgdorferi / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D054884:Host-Pathogen Interactions; D047468:Immunoprecipitation; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism*; D008193:Lyme Disease / Q000635:transmission*; D051379:Mice; D008809:Mice, Inbred C3H; D050296:Microbial Viability; D013987:Ticks / Q000382:microbiology*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D008074:Lipoproteins
keywords: Borrelia burgdorferi; La7 protein; Lyme disease; Tick-borne; Transmission