title: New tick defensin isoform and antimicrobial gene expression in response to Rickettsia montanensis challenge.
abstract: Recent studies aimed at elucidating the rickettsia-tick interaction have discovered that the spotted fever group rickettsia Rickettsia montanensis, a relative of R. rickettsii, the etiologic agent of Rocky Mountain spotted fever, induces differential gene expression patterns in the ovaries of the hard tick Dermacentor variabilis. Here we describe a new defensin isoform, defensin-2, and the expression patterns of genes for three antimicrobials, defensin-1 (vsnA1), defensin-2, and lysozyme, in the midguts and fat bodies of D. variabilis ticks that were challenged with R. montanensis. Bioinformatic and phylogenetic analyses of the primary structure of defensin-2 support its role as an antimicrobial. The tissue distributions of the three antimicrobials, especially the two D. variabilis defensin isoforms, are markedly different, illustrating the immunocompetence of the many tissues that R. montanensis presumably invades once acquired by the tick. Antimicrobial gene expression patterns in R. montanensis-challenged ticks suggest that antimicrobial genes play a role during the acquisition-invasion stages in the tick.
authors.affiliation: Department of Microbiology and Immunology, University of Maryland School of Medicine, 660 West Redwood St., HH Room 324, Baltimore, MD 21201, USA. scera001@umaryland.edu
authors.forename: Shane M
authors.initials: SM
authors.lastname: Ceraul
authors.forename: Sheila M
authors.initials: SM
authors.lastname: Dreher-Lesnick
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Gillespie
authors.forename: M Sayeedur
authors.initials: MS
authors.lastname: Rahman
authors.forename: Abdu F
authors.initials: AF
authors.lastname: Azad
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004247:DNA / Q000737:chemistry / Q000235:genetics; D023082:Defensins / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification; D003870:Dermacentor / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology*; D005260:Female; D041981:Gastrointestinal Tract / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D015870:Gene Expression; D020869:Gene Expression Profiling; D008969:Molecular Sequence Data; D009113:Muramidase / Q000096:biosynthesis / Q000235:genetics*; D010802:Phylogeny; D020033:Protein Isoforms / Q000096:biosynthesis* / Q000235:genetics / Q000302:isolation & purification; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012281:Rickettsia / Q000276:immunology*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D023082:Defensins; D020033:Protein Isoforms; D004247:DNA; D009113:Muramidase