Department of Paraclinical Sciences, Norwegian University of Life Sciences, Oslo, Norway.
Fish Vet Group, Oslo, Norway.
J Fish Dis. 2021 Jul;44(7):923-937. doi: 10.1111/jfd.13352. Epub 2021 Feb 16.
Pancreas disease (PD) is a serious challenge in European salmonid aquaculture caused by salmonid alphavirus (SAV). In this study, we report the effect of immunization of Atlantic salmon with three attenuated infectious SAV3 strains with targeted mutations in a glycosylation site of the envelope E2 protein and/or in a nuclear localization signal in the capsid protein. In a pilot experiment, it was shown that the mutated viral strains replicated in fish, transmitted to naïve cohabitants and that the transmission had not altered the sequences. In the main experiment, the fish were immunized with the strains and challenged with SAV3 eight weeks after immunization. Immunization resulted in infection both in injected fish and 2 weeks later in the cohabitant fish, followed by a persistent but declining load of the mutated virus variants in the hearts. The immunized fish developed clinical signs and pathology consistent with PD prior to challenge. However, fish injected with the virus mutated in both E2 and capsid showed little clinical signs and had higher average weight gain than the groups immunized with the single mutated variants. The SAV strain used for challenge was not detected in the immunized fish indicating that these fish were protected against superinfection with SAV during the 12 weeks of the experiment.
胰腺病（PD）是欧洲鲑鱼养殖业面临的一个严重挑战，由鲑鱼甲病毒（SAV）引起。在本研究中，我们报告了用三种在包膜 E2 蛋白糖基化位点和/或衣壳蛋白核定位信号处具有靶向突变的减毒传染性 SAV3 株对大西洋鲑进行免疫的效果。在一项初步实验中，表明突变病毒株在鱼类中复制，传播给未感染的同居者，并且传播没有改变序列。在主要实验中，鱼在免疫后 8 周用这些菌株进行免疫接种并接受 SAV3 挑战。免疫接种导致注射鱼和 2 周后同居鱼感染，随后心脏中突变病毒变体的负荷持续但下降。在接受挑战之前，免疫接种的鱼出现了与 PD 一致的临床症状和病理学表现。然而，与免疫接种单一突变变体的组相比，同时在 E2 和衣壳中发生突变的病毒株注射的鱼表现出很少的临床症状，并且平均体重增加更高。用于挑战的 SAV 株未在免疫鱼中检测到，这表明这些鱼在实验的 12 周内免受 SAV 的再次感染。
