Hynes Wayne L, Stokes Martha M, Hensley Shannon M, Todd S Michelle, Sonenshine Daniel E
Department of Biological Sciences, Old Dominion University, Norfolk, VA 23529-0266, USA.
Exp Appl Acarol. 2008 Dec;46(1-4):7-15. doi: 10.1007/s10493-008-9158-6. Epub 2008 May 28.
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.
防御素是蜱先天免疫系统的重要组成部分。这些小肽由不同属的蜱产生，并在各种组织中表达。在本研究中，我们使用RNA干扰来沉默美国犬蜱（变异革蜱）血细胞产生的防御素varisin的表达。在将蜱放置在兔子身上之前，给它们注射双链varisin RNA。喂食后，将蜱取出、放血，并分离血淋巴血浆和血细胞。筛选血细胞中varisin转录本和肽的存在（或不存在）情况。varisin肽低于可检测水平，并且转录本显示敲低率大于99%。与注射对照的蜱相比，血淋巴血浆的抗菌活性降低了2至4倍，这表明varisin占血淋巴抗菌活性的很大一部分。
