Abstract Infectious pancreatic necrosis virus (IPNV) causes severe viral disease in salmonids, with major economic losses in the global rainbow trout aquaculture industry following from a high mortality rate. In the present study, we aimed to develop a safe and efficient vaccine to protect rainbow trout against IPNV infection. Administered via the immersion route, a live vector vaccine containing the coding region of the IPNV VP2 induced protective immune responses in rainbow trout. For best protection, juvenile rainbow trout should be immunized with a 1:100 dilution of the titer with 1 × 1010.0 ml−1 TCID50 of the live vector vaccine, via 10-min immersion. Expression of the IPNV VP2 gene was confirmed in spleens of vaccinated rainbow trout, and reached the highest level at 3 days post-vaccination (dpv) and thereafter gradually decreased between 3 and 15 dpv. The expression of TLR-3, TLR-7 and TLR-8 was upregulated after vaccination, and the highest expression levels of IFN-1, Mx-1, Mx-3, Vig-1 and Vig-2 were detected at 3 dpv. Four markers of the adaptive immune response (CD4, CD8, IgM and IgT) were continuously increased in the spleens of vaccinated fish as compared with controls, between 3 and 15 dpv. The cumulative percentage mortality differed significantly between the vaccinated fish and the controls (empty-plasmid-vaccinated). The results of the IPNV challenge showed that the live vector vaccine had a high protection rate against IPNV (relative percent survival value of 88.24), and the vaccinated rainbow trout displayed high levels of serum antibodies against IPNV infection. Taken together, our results demonstrate that this is a promising live vector vaccine that could be used to protect rainbow trout against IPNV infection.

中文翻译：

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虹鳟感染性胰腺坏死病毒活载体疫苗的研制

摘要 传染性胰腺坏死病毒（IPNV）在鲑鱼中引起严重的病毒性疾病，高死亡率给全球虹鳟鱼养殖业带来重大经济损失。在本研究中，我们旨在开发一种安全有效的疫苗来保护虹鳟鱼免受 IPNV 感染。通过浸入途径给药，含有 IPNV VP2 编码区的活载体疫苗在虹鳟鱼中诱导保护性免疫反应。为获得最佳保护，幼虹鳟鱼应使用 1 × 1010.0 ml-1 TCID50 活载体疫苗的滴度 1:100 稀释，浸泡 10 分钟。IPNV VP2 基因在接种过的虹鳟鱼的脾脏中的表达得到证实，并在接种后 3 天 (dpv) 达到最高水平，此后在 3 至 15 dpv 之间逐渐下降。接种疫苗后TLR-3、TLR-7和TLR-8的表达上调，在3 dpv时检测到​​IFN-1、Mx-1、Mx-3、Vig-1和Vig-2的最高表达水平。与对照组相比，在 3 到 15 dpv 之间，免疫鱼的脾脏中的四种适应性免疫反应标志物（CD4、CD8、IgM 和 IgT）持续增加。接种疫苗的鱼和对照（接种空质粒）之间的累积死亡率百分比显着不同。IPNV攻击的结果表明，活载体疫苗对IPNV具有很高的保护率（相对存活率为88.24），接种的虹鳟鱼显示出高水平的IPNV感染血清抗体。