title: Using RNA interference to determine the role of varisin in the innate immune system of the hard tick Dermacentor variabilis (Acari: Ixodidae).
abstract: Defensins are an important component of the innate immune system of ticks. These small peptides are produced by various genera of ticks, and expressed in various tissues. In this study we used RNA interference to silence the expression of the defensin varisin produced by the hemocytes of the American dog tick, Dermacentor variabilis. Ticks were injected with double stranded varisin RNA prior to being placed on a rabbit. After feeding, the ticks were removed, bled, and the hemolymph plasma and hemocytes separated. Hemocytes were screened for the presence (or absence) of both varisin transcript and peptide. Varisin peptide was below detectable levels and the transcript showed a greater than 99% knockdown. The antimicrobial activity of the hemolymph plasma was reduced 2-4 fold compared to that of control injected ticks indicating varisin accounts for a large portion of the antimicrobial activity of the hemolymph.
authors.affiliation: Department of Biological Sciences, Old Dominion University, Norfolk, VA 23529-0266, USA. whynes@odu.edu
authors.forename: Wayne L
authors.initials: WL
authors.lastname: Hynes
authors.forename: Martha M
authors.initials: MM
authors.lastname: Stokes
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Hensley
authors.forename: S Michelle
authors.initials: SM
authors.lastname: Todd
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Sonenshine
mesh_terms: D000818:Animals; D023082:Defensins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D003870:Dermacentor / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D005260:Female; D006434:Hemocytes / Q000378:metabolism; D006458:Hemolymph / Q000276:immunology*; D007113:Immunity, Innate; D016133:Polymerase Chain Reaction; D034622:RNA Interference; D011817:Rabbits
chemical_list: D023082:Defensins