INSECT IMMUNE EVASION BY DAUER AND NONDAUER ENTOMOPATHOGENIC NEMATODES
INSECT IMMUNE EVASION BY DAUER AND NONDAUER ENTOMOPATHOGENIC NEMATODES
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DOI：
10.1645/20-61
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发表时间：
2021-01-01
影响因子：
1.3
通讯作者：
Contreras-Garduno, Jorge
中科院分区：
文献类型：
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作者：
Lara-Reyes, Nancy;Guillermo Jimenez-Cortes, J.;Contreras-Garduno, Jorge
包括昆虫在内的动物的免疫反应会被一些寄生虫克服。例如，专性昆虫病原线虫(EPN)异形线虫和斯氏线虫的Dauer幼虫可以入侵昆虫，逃避它们的防御，并导致死亡。虽然长久以来一直认为DL是线虫的唯一侵染期，但最近的报道表明，兼性EPN的L2-L3幼虫也具有杀死昆虫的能力。据我们所知，目前还没有关于非免疫屏障(外骨骼及其开口)在避免被DL和L2-L3幼虫感染方面的作用，或者这些幼虫是否以同样的方式逃避宿主免疫系统的研究。本研究的目的是通过用兼性寄生线虫Rhabditis Regina感染Galeria mellonella来检验这些问题。将DL或L2-L3幼虫寄生在蛾上或其附近，或注入蛾的血腔内。一旦线虫到达血腔，下列宿主免疫反应参数被量化：酚氧化酶原、酚氧化酶、裂解活性和颗粒血细胞的数量。DL对外骨骼的穿透能力强于L2-L3幼虫。然而，一旦进入体内，这两种昆虫都没有被免疫系统注意到，并杀死了昆虫。L2-L3幼虫激活的颗粒血细胞数量高于Dl幼虫。我们首次证明了L2-L3幼虫可以穿透和逃避昆虫的免疫系统。还需要进一步的研究来比较兼性和特化的EPN，以确定哪种更有可能与DL和L2-L3幼虫一起逃避昆虫防御屏障并产生死亡。这些结果将有助于理解昆虫病原线虫毒力的进化。
The immune response of animals, including insects, is overcome by some parasites. For example, dauer larvae (DL) of the obligate entomopathogenic nematodes (EPNs) Heterorhabditis and Steinernema can invade insects, evade their defenses, and cause death. Although DL were long assumed to be the only infective stage of nematodes, recent reports suggest that L2-L3 larvae of facultative EPNs are also capable of killing insects. There are no studies, to our knowledge, about the role of nonimmunological barriers (the exoskeleton and its openings) in avoiding infection by DL and L2-L3 larvae, or whether these larval stages evade the host immune system in the same way. The objective of this study was to examine these questions by infecting Galleria mellonella with the facultative parasitic nematode Rhabditis regina. DL or L2-L3 larvae were either deposited on or near the moths or injected into their hemocoel. Once nematodes reached the hemocoel, the following host immune response parameters were quantified: prophenoloxidase, phenoloxidase, lytic activity, and the number of granular hemocytes. DL showed a greater ability to penetrate the exoskeleton than L2-L3 larvae. Once inside, however, both went unnoticed by the immune system and killed the insect. A higher number of granular hemocytes was activated by L2-L3 larvae than DL. We show for the first time that L2-L3 larvae can penetrate and evade the insect immune system. Further research is needed to compare facultative and specialized EPNs to determine which is more likely, with both DL and L2-L3 larvae, to evade insect defense barriers and produce death. The results will contribute to understanding the evolution of virulence in entomopathogenic nematodes.