Hajnická V, Kocakova P, Slovak M, Labuda M, Fuchsberger N, Nuttall P A
Institute of Preventive and Clinical Medicine, Bratislava, Slovakia.
Parasite Immunol. 2000 Apr;22(4):201-6. doi: 10.1046/j.1365-3024.2000.00296.x.
The saliva of haematophagous arthropods (e.g. mosquitoes, sandflies and ticks) contains potent immunomodulatory activities that counter their hosts' haemostatic, inflammatory and immune responses to facilitate blood-feeding. Such effects are exploited by arthropod-transmitted pathogens to promote their transmission. We investigated the ability of tick saliva to enhance arthropod-borne virus (arbovirus) transmission by determining its effect on the antiviral action of murine interferon (IFN alpha/beta). Salivary gland extract (SGE) was prepared from partially fed adult female Dermacentor reticulatus ticks that had been feeding on mice for either 3 or 5 days (SGED3 and SGED5, respectively). We demonstrated that SGE inhibits the antiviral effect of IFN as measured by a biological assay using vesicular stomatitis virus (VSV), and by two-dimensional electrophoretic analysis of the appearance of selected VSV proteins. The most pronounced effect was observed when mouse L cells were treated with SGE prior to IFN treatment. Following pretreatment with SGE, virus multiplication (which was fully blocked by IFN treatment alone) achieved yields similar to those obtained from infected cells not treated with IFN. Contemporaneous treatment, or treatment with SGE after IFN, was less effective. In parallel with these findings, formation of early viral proteins, N (nucleocapsid protein) and P (phosphoprotein), which was blocked by IFN, was detectable following pretreatment with SGE. The ability to inhibit the antiviral action of IFN was higher for SGED3 compared to SGED5. Demonstration that tick SGE can promote virus replication by suppressing the action of IFN helps explain why ticks are such efficient vectors of arboviruses.
吸血节肢动物（如蚊子、白蛉和蜱虫）的唾液具有强大的免疫调节活性，可对抗宿主的止血、炎症和免疫反应，以促进吸血。节肢动物传播的病原体利用这些作用来促进自身传播。我们通过确定蜱虫唾液对小鼠干扰素（IFNα/β）抗病毒作用的影响，研究了其增强节肢动物传播病毒（虫媒病毒）传播的能力。从分别以小鼠为食3天和5天的部分饱血成年雌性网纹革蜱制备唾液腺提取物（SGE）（分别为SGED3和SGED5）。我们证明，通过使用水疱性口炎病毒（VSV）的生物学测定以及对选定VSV蛋白出现情况的二维电泳分析，SGE可抑制IFN的抗病毒作用。当在IFN处理之前用SGE处理小鼠L细胞时，观察到最明显的效果。用SGE预处理后，病毒增殖（单独用IFN处理可完全阻断）产生的产量与未用IFN处理的感染细胞相似。同时处理或在IFN后用SGE处理效果较差。与这些发现同时，在用SGE预处理后，可检测到被IFN阻断的早期病毒蛋白N（核衣壳蛋白）和P（磷蛋白）的形成。与SGED5相比，SGED3抑制IFN抗病毒作用的能力更高。证明蜱虫SGE可通过抑制IFN的作用来促进病毒复制，这有助于解释为什么蜱虫是如此高效的虫媒病毒载体。
