Skugor Stanko, Glover Kevin Alan, Nilsen Frank, Krasnov Aleksei
Nofima Akvaforsk Fiskeriforskning, POBox 5010, As 1430, Norway.
BMC Genomics. 2008 Oct 23;9:498. doi: 10.1186/1471-2164-9-498.
The salmon louse (SL) is an ectoparasitic caligid crustacean infecting salmonid fishes in the marine environment. SL represents one of the major challenges for farming of salmonids, and veterinary intervention is necessary to combat infection. This study addressed gene expression responses of Atlantic salmon infected with SL, which may account for its high susceptibility.
The effects of SL infection on gene expression in Atlantic salmon were studied throughout the infection period from copepodids at 3 days post infection (dpi) to adult lice (33 dpi). Gene expression was analyzed at three developmental stages in damaged and intact skin, spleen, head kidney and liver, using real-time qPCR and a salmonid cDNA microarray (SFA2). Rapid detection of parasites was indicated by the up-regulation of immunoglobulins in the spleen and head kidney and IL-1 receptor type 1, CD4, beta-2-microglobulin, IL-12beta, CD8alpha and arginase 1 in the intact skin of infected fish. Most immune responses decreased at 22 dpi, however, a second activation was observed at 33 dpi. The observed pattern of gene expression in damaged skin suggested the development of inflammation with signs of Th2-like responses. Involvement of T cells in responses to SL was witnessed with up-regulation of CD4, CD8alpha and programmed death ligand 1. Signs of hyporesponsive immune cells were seen. Cellular stress was prevalent in damaged skin as seen by highly significant up-regulation of heat shock proteins, other chaperones and mitochondrial proteins. Induction of the major components of extracellular matrix, TGF-beta and IL-10 was observed only at the adult stage of SL. Taken together with up-regulation of matrix metalloproteinases (MMP), this classifies the wounds afflicted by SL as chronic. Overall, the gene expression changes suggest a combination of chronic stress, impaired healing and immunomodulation. Steady increase of MMP expression in all tissues except liver was a remarkable feature of SL infected fish.
SL infection in Atlantic salmon is associated with a rapid induction of mixed inflammatory responses, followed by a period of hyporesponsiveness and delayed healing of injuries. Persistent infection may lead to compromised host immunity and tissue self-destruction.
鲑鱼虱（SL）是一种寄生于鲑科鱼类体表的寄生性哲水蚤类甲壳动物，存在于海洋环境中。SL是鲑科鱼类养殖面临的主要挑战之一，需要兽医干预以对抗感染。本研究探讨了感染SL的大西洋鲑的基因表达反应，这可能是其易感性高的原因。
在感染期（从感染后3天的无节幼体到33天的成体虱子）对感染SL的大西洋鲑的基因表达影响进行了研究。使用实时定量PCR和鲑科鱼类cDNA微阵列（SFA2），在受损和完整皮肤、脾脏、头肾和肝脏的三个发育阶段分析基因表达。脾脏和头肾中免疫球蛋白的上调以及感染鱼完整皮肤中白细胞介素-1受体1型、CD4、β-2微球蛋白、白细胞介素-12β、CD8α和精氨酸酶1的上调表明寄生虫被快速检测到。大多数免疫反应在感染后22天下降，然而，在33天观察到第二次激活。受损皮肤中观察到的基因表达模式表明炎症发展伴有类似Th2反应的迹象。CD4、CD8α和程序性死亡配体1的上调证明T细胞参与了对SL的反应。可见免疫细胞反应低下的迹象。热休克蛋白、其他伴侣蛋白和线粒体蛋白的高度显著上调表明细胞应激在受损皮肤中普遍存在。仅在SL的成体阶段观察到细胞外基质的主要成分转化生长因子-β和白细胞介素-10的诱导。与基质金属蛋白酶（MMP）的上调一起，这将SL造成的伤口归类为慢性伤口。总体而言，基因表达变化表明慢性应激、愈合受损和免疫调节的综合作用。除肝脏外，所有组织中MMP表达的稳定增加是感染SL的鱼的一个显著特征。
大西洋鲑感染SL与混合性炎症反应的快速诱导有关，随后是一段时间的反应低下和伤口愈合延迟。持续感染可能导致宿主免疫力受损和组织自我破坏。
