Activation of host constitutive immune defence by an intestinal trypanosome parasite of bumble bees
Activation of host constitutive immune defence by an intestinal trypanosome parasite of bumble bees
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DOI：
10.1017/s0031182002002755
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发表时间：
2003-03-01
期刊：
影响因子：
2.4
通讯作者：
Schmid-Hempel, P
中科院分区：
文献类型：
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作者：
Brown, MJF;Moret, Y;Schmid-Hempel, P
许多寄生虫，包括影响人类和牲畜的重要物种，必须在昆虫肠道的恶劣环境中生存，以完成其生命周期。因此，了解昆虫如何保护自己免受这种寄生虫的侵害具有直接的实际意义。以前，这种保护被认为主要由机械结构和凝集素的作用组成。然而，最近很明显，肠道感染可能以更复杂的方式与宿主免疫系统相互作用。在这里，使用谦虚的蜜蜂，熊蜂terrestris和他们的非侵入性肠道锥虫，Crithidia bombi，作为一个模型系统，我们调查了寄生虫感染，宿主资源和感染的持续时间对宿主免疫系统的影响。我们发现，感染增加了一倍的常设水平的免疫防御血淋巴（组成型酚氧化酶系统），这是用来作为第一，一般防御寄生虫。然而，寄生虫从血淋巴中的物理分离表明肠道和控制酚氧化酶原系统的基因之间存在信使系统。令人惊讶的是，我们发现宿主资源压力或感染持续时间对免疫系统没有直接影响。我们的研究结果表明，昆虫对肠道感染的一种新的战术反应，证明了这种宿主-寄生虫系统的复杂性。
Many parasites, including important species that affect humans and livestock, must survive the harsh environment of insect guts to complete their life-cycle. Hence, understanding how insects protect themselves against such parasites has immediate practical implications. Previously, such protection has been thought to consist mainly of mechanical structures and the action of lectins. However, recently it has become apparent that gut infections may interact with the host immune system in more complex ways. Here, using humble bees, Bombus terrestris and their non-invasive gut trypanosome, Crithidia bombi, as a model system we investigated the effects of parasitic infection, host resources and the duration of infections on the host immune system. We found that infection doubled standing levels of immune defence in the haemolymph (the constitutive pro-phenoloxidase system), which is used as a first, general defence against parasites. However, physical separation of the parasite from the haemolymph suggests the presence of a messenger system between the gut and the genes that control the pro-phenoloxidase system. Surprisingly, we found no direct effect of host resource-stress or duration of the infection on the immune system. Our results suggest a novel and tactical response of insects to gut infections, demonstrating the complexity of such host-parasite systems.