Ixodes scapularis is the major vector of Lyme disease in the Eastern United States. Each active life stage (larva, nymph, and adult) takes a blood meal either for developing and molting to the next stage (larvae and nymphs) or for oviposition (adult females). This protein-rich blood meal is the only food taken by Ixodes ticks and therefore efficient blood digestion is critical for survival. Studies in partially engorged ticks have shown that the initial stages of digestion are carried out by cathepsin proteases within acidic digestive cells. In this study, we investigated the potential role of serine proteases in blood digestion in replete ticks. RNA interference was used for functional analysis and a trypsin-benzoyl-D, L-arginine 4-nitoanilide assay was used to measure active trypsin levels. Hemoglobinolytic activity was determined in vitro, with or without a serine protease inhibitor. Our data suggest that trypsin levels increase significantly after repletion. Knockdown of serine proteases negatively impacted blood feeding, survival, fecundity, levels of active trypsin in the midgut, and resulted in lower hemoglobin degradation. Incubation of midgut extract with a trypsin inhibitor resulted in 65% lower hemoglobin degradation. We provide evidence of the serine proteases as digestive enzymes in fully engorged, replete females. Understanding the digestive profile of trypsin during blood meal digestion in I. scapularis improves our understanding of the basic biology of ticks and may lead to new methods for tick control.

中文翻译：

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胰蛋白酶样丝氨酸蛋白酶在充足的莱姆病载体Vector虫肩I小中的血液消化。

肩cap龙虾是美国东部莱姆病的主要传播媒介。每个活跃的生命阶段（幼虫，若虫和成虫）都会进食血粉，以发育和蜕皮到下一个阶段（幼虫和若虫）或产卵（成年雌性）。这种富含蛋白质的血粉是艾克多斯唯一的食物，因此有效的血液消化对于生存至关重要。对部分饱食的s的研究表明，消化的初始阶段是由酸性消化细胞内的组织蛋白酶进行的。在这项研究中，我们调查了丝氨酸蛋白酶在大量壁虱血液消化中的潜在作用。RNA干扰用于功能分析，胰蛋白酶-苯甲酰基-D，L-精氨酸4-硝基苯胺测定法用于测量活性胰蛋白酶水平。在有或没有丝氨酸蛋白酶抑制剂的条件下测定了血红蛋白分解活性。我们的数据表明，补充胰岛素后胰蛋白酶水平显着增加。敲除丝氨酸蛋白酶会对中肠的血液供应，存活率，繁殖力，活性胰蛋白酶水平产生负面影响，并导致较低的血红蛋白降解。将中肠提取物与胰蛋白酶抑制剂一起孵育可使血红蛋白降解降低65％。我们提供了丝氨酸蛋白酶作为饱腹，充血雌性中的消化酶的证据。了解胰蛋白酶消化过程中的血粉消化肩cap鱼提高了我们对tick虫基本生物学的理解，并可能导致控制tick虫的新方法。