Institute of Marine Research, P.O. Box 1870, Nordnes, 5817 Bergen, Norway.
Institute of Marine Research, P.O. Box 1870, Nordnes, 5817 Bergen, Norway; Department of Biology, University of Bergen, P.O. Box 7803, 5020 Bergen, Norway.
Fish Shellfish Immunol. 2018 Mar;74:573-583. doi: 10.1016/j.fsi.2017.12.017. Epub 2018 Jan 17.
Pancreas disease (PD) caused by salmonid alphavirus (SAV) is the most serious viral disease in Norwegian aquaculture. Study of the immune response to SAV will aid preventative measures including vaccine development. The innate immune response was studied in Atlantic salmon infected by either bath immersion (BI) or by intra-muscular (i.m.) injection (IM) with SAV subtype 3, two and nine weeks after seawater transfer (Phases A and B respectively). Phase A results have been previously published (Moore et al., 2017) and Phase B results are presented here together with a comparison of results achieved in Phase A. There was a rapid accumulation of infected fish in the IM-B (IM Phase B) group and all fish sampled were SAV RNA positive by 7 dpi (days post infection). In contrast, only a few SAV RNA positive (infected) fish were identified at 14, 21 and 28 dpi in the BI-B (BI Phase B) group. Differences in the transcription of several immune genes were apparent when compared between the infected fish in the IM-B and BI-B groups. Transcription of the analysed genes peaked at 7 dpi in the IM-B group and at 14 dpi in the BI-B group. However, this latter finding was difficult to interpret due to the low prevalence of SAV positive fish in this group. Additionally, fish positive for SAV RNA in the BI-B group showed higher transcription of IL-1β, IFNγ and CXCL11_L1, all genes associated with the inflammatory response, compared to the IM-B group. Histopathological changes in the heart were restricted to the IM-B group, while (immune) cell filtration into the pancreas was observed in both groups. Compared to the Phase A fish that were exposed to SAV3 two weeks after seawater transfer, the Phase B fish in the current paper, showed a higher and more sustained innate immune gene transcription in response to the SAV3 infection. In addition, the basal transcription of several innate immune genes in non-infected control fish in Phase B (CT-B) was also significantly different when compared to Phase A control fish (CT-A).
鲑鱼甲病毒（SAV）引起的胰腺疾病（PD）是挪威水产养殖中最严重的病毒性疾病。对 SAV 的免疫反应研究将有助于包括疫苗开发在内的预防措施。本研究通过对大西洋鲑进行经口感染（BI）或肌肉内（IM）注射感染 SAV 亚型 3（分别在海水转移后的第 2 周和第 9 周，即 A 期和 B 期），研究了其先天免疫反应。A 期的结果已发表（Moore 等人，2017 年），B 期的结果在此呈现，并与 A 期的结果进行了比较。IM-B（IM 期 B）组中迅速积累了受感染的鱼类，所有在第 7 天取样的鱼类均为 SAV RNA 阳性。相比之下，在 BI-B（BI 期 B）组中，在第 14、21 和 28 天取样时，只有少数 SAV RNA 阳性（感染）鱼类被鉴定。与 IM-B 和 BI-B 两组中感染鱼类相比，几种免疫基因的转录存在明显差异。IM-B 组中分析基因的转录在第 7 天达到峰值，而 BI-B 组在第 14 天达到峰值。然而，由于该组中 SAV 阳性鱼类的比例较低，因此很难解释这一结果。此外，在 BI-B 组中，SAV RNA 阳性的鱼类表现出更高的 IL-1β、IFNγ 和 CXCL11_L1 的转录，所有这些基因都与炎症反应有关，与 IM-B 组相比。心脏的组织病理学变化仅限于 IM-B 组，而在两组中均观察到（免疫）细胞滤入胰腺。与在海水转移后两周接触 SAV3 的 A 期鱼类相比，在本论文中 B 期鱼类对 SAV3 感染的先天免疫基因转录表现出更高和更持续的反应。此外，B 期非感染对照鱼类（CT-B）中几种先天免疫基因的基础转录与 A 期对照鱼类（CT-A）也有显著差异。
