title: Functional characterization of two defensin isoforms of the hard tick Ixodes ricinus.
abstract: BACKGROUND
  The immune system of ticks is stimulated to produce many pharmacologically active molecules during feeding and especially during pathogen invasion. The family of cationic peptides - defensins - represents a specific group of antimicrobial compounds with six conserved cysteine residues in a molecule.
  
  
  RESULTS
  Two isoforms of the defensin gene (def1 and def2) were identified in the European tick Ixodes ricinus. Expression of both genes was induced in different tick organs by a blood feeding or pathogen injection. We have tested the ability of synthetic peptides def1 and def2 to inhibit the growth or directly kill several pathogens. The antimicrobial activities (expressed as minimal inhibition concentration and minimal bactericidal concentration values) against Gram positive bacteria were confirmed, while Gram negative bacteria, yeast, Tick Borne Encephalitis and West Nile Viruses were shown to be insensitive. In addition to antimicrobial activities, the hemolysis effect of def1 and def2 on human erythrocytes was also established.
  
  
  CONCLUSIONS
  Although there is nothing known about the realistic concentration of defensins in I. ricinus tick body, these results suggest that defensins play an important role in defence against different pathogens. Moreover this is a first report of a one amino acid substitution in a defensins molecule and its impact on antimicrobial activity.
authors.affiliation: University of South Bohemia, Faculty of Science, České Buděovice, Czech Republic. terezam@paru.cas.cz
authors.forename: Tereza
authors.initials: T
authors.lastname: Chrudimská
authors.forename: Jiřina
authors.initials: J
authors.lastname: Slaninová
authors.forename: Nataliia
authors.initials: N
authors.lastname: Rudenko
authors.forename: Daniel
authors.initials: D
authors.lastname: Růžek
authors.forename: Libor
authors.initials: L
authors.lastname: Grubhoffer
mesh_terms: D000825:Animal Structures / Q000276:immunology; D000818:Animals; D000890:Anti-Infective Agents / Q000302:isolation & purification / Q000494:pharmacology; D023082:Defensins / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D004912:Erythrocytes / Q000187:drug effects; D005260:Female; D020869:Gene Expression Profiling; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006168:Guinea Pigs; D006801:Humans; D018884:Ixodes / Q000235:genetics / Q000276:immunology*; D008826:Microbial Sensitivity Tests; D020033:Protein Isoforms / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D014780:Viruses / Q000187:drug effects; D015003:Yeasts / Q000187:drug effects
chemical_list: D000890:Anti-Infective Agents; D023082:Defensins; D020033:Protein Isoforms