RNAi suppression of recognition protein mediated immune responses in the tobacco hornworm Manduca sexta causes increased susceptibility to the insect pathogen Photorhabdus
RNAi suppression of recognition protein mediated immune responses in the tobacco hornworm Manduca sexta causes increased susceptibility to the insect pathogen Photorhabdus
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DOI：
10.1016/j.dci.2006.02.008
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发表时间：
2006-01-01
影响因子：
2.9
通讯作者：
Reynolds, Stuart E.
中科院分区：
文献类型：
--
作者：
Eleftherianos, Ioannis;Millichap, Peter J.;Reynolds, Stuart E.
细菌病原体要么隐藏起来，要么克服宿主的免疫反应。在这里，我们证明了两种不同的昆虫病原菌，发光光杆菌TT01和共生光杆菌ATCC43949，都被它们的寄主Manduca sexta的免疫系统识别，这表明编码三种不同的诱导微生物识别蛋白的mRNAs的水平迅速上升，这三种蛋白是血球蛋白，免疫凝集素-2和肽聚糖识别蛋白。RNA干扰(RNAi)通过注射双链RNA(DsRNA)在mRNA和蛋白质水平上抑制这些基因的表达。当这些基因中的任何一个被敲除时，昆虫抵抗感染的能力显著降低，这是通过感染昆虫的死亡速度来衡量的。针对Im ulectin-2的RNAi使寄主对感染的抵抗力最大地降低。对感染抵抗力的降低与血淋巴酚氧化酶活性的降低有关。这些结果表明，光杆藻不仅被六钩藻免疫系统识别，而且昆虫的免疫系统在抵抗感染方面发挥着积极的、但最终无效的作用。(C)2006爱思唯尔有限公司。保留所有权利。
Bacterial pathogens either hide from or overcome the immune response of their hosts. Here we show that two different species of insect pathogenic bacteria, Photorhabdus luminescens TT01 and Photorhabdus asymbiotica ATCC43949, were both recognized by the immune system of their host Manduca sexta, as indicated by a rapid increase in the levels of mRNAs encoding three different inducible microbial recognition proteins, Hemolin, Immulectin-2 and peptidoglycan recognition protein. RNA interference (RNAi)-mediated inhibition of expression ("knock-down") of each of these genes at the level of both mRNA and protein was achieved through injection of double-stranded RNA (dsRNA). Knock-down of any one of these genes markedly decreased the ability of the insects to withstand infection when exposed to either species of Photorhabdus, as measured by the rate at which infected insects died. RNAi against Immulectin-2 caused the greatest reduction in host resistance to infection. The decreased resistance to infection was associated with reduced hemolymph phenoloxidase activity. These results show not only that Photorhabdus is recognized by the Manduca sexta immune system but also that the insect's immune system plays an active, but ultimately ineffective, role in countering infection. (c) 2006 Elsevier Ltd. All rights reserved.