Marine Microbial Pathogenesis and Vaccinology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada.
Fish Physiology Laboratory, Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada.
Fish Shellfish Immunol. 2020 Sep;104:557-566. doi: 10.1016/j.fsi.2020.06.005. Epub 2020 Jun 24.
Effective vaccine programs against Aeromonas salmonicida have been identified as a high priority area for the sablefish (Anoplopoma fimbria) aquaculture. In this study, we established an A. salmonicida infection model in sablefish to evaluate the efficacy of commercial vaccines and an autogenous vaccine preparation. Groups of 40 fish were intraperitoneally (ip) injected with different doses of A. salmonicida J410 isolated from infected sablefish to calculate the median lethal dose (LD). Samples of blood, head kidney, spleen, brain, and liver were also collected at different time points to determine the infection kinetics. The LD was estimated as ~3 × 10 CFU/dose. To evaluate the immune protection provided by an autogenous vaccine and two commercial vaccines in a common garden experimental design, 140 fish were PIT-tagged, vaccinated and distributed equally into 4 tanks (35 fish for each group, including a control group). Blood samples were taken every 2 weeks to evaluate IgM titers. At 10 weeks post-immunization, all groups were ip challenged with 100 times the calculated LD for A. salmonicida J410. A. salmonicida was detected after 5 days post-infection (dpi) in all collected tissues. At 30 days post-challenge the relative percentage survival (RPS) with respect to the control group was calculated for each vaccine. The RPS for the bacterin mix was 65.22%, for Forte Micro 4® vaccine was 56.52% and for Alpha Ject Micro 4® was 30.43%, and these RPS values were reflected by A. salmonicida tissue colonization levels at 10 days post-challenge. Total IgM titers peaked at 6-8 weeks post-immunization, where the autogenous vaccine group showed the highest IgM titers and these values were consistent with the RPS data. Also, we determined that the A. salmonicida A-layer binds to immunoglobulins F(ab)' in a non-specific fashion, interfering with immune assays and potentially vaccine efficacy. Our results indicate that vaccine design influences sablefish immunity and provide a guide for future sablefish vaccine programs.
有效的鲑鱼气单胞菌疫苗方案已被确定为黑鮟鱇（Anoplopoma fimbria）水产养殖的一个高度优先领域。在这项研究中，我们建立了黑鮟鱇的鲑鱼气单胞菌感染模型，以评估商业疫苗和同源疫苗制剂的功效。将 40 条鱼分别经腹腔（ip）注射不同剂量的源自感染黑鮟鱇的鲑鱼气单胞菌 J410 来计算半数致死剂量（LD）。在不同时间点采集血液、头肾、脾脏、大脑和肝脏样本，以确定感染动力学。LD 估计约为 3×10 CFU/剂量。为了在普通花园实验设计中评估同源疫苗和两种商业疫苗提供的免疫保护，将 140 条鱼进行 PIT 标记、接种并平均分配到 4 个水箱（每组 35 条鱼，包括对照组）。每两周采集一次血液样本，以评估 IgM 滴度。免疫后 10 周，所有组均经腹腔注射计算出的 100 倍 LD 的鲑鱼气单胞菌 J410。感染后 5 天在所有采集的组织中均检测到鲑鱼气单胞菌。攻毒后 30 天，根据对照组计算每种疫苗的相对存活率（RPS）。菌苗混合物的 RPS 为 65.22%，Forte Micro 4®疫苗为 56.52%，Alpha Ject Micro 4®疫苗为 30.43%，这些 RPS 值反映了攻毒后 10 天的鲑鱼气单胞菌组织定植水平。总 IgM 滴度在免疫后 6-8 周达到峰值，同源疫苗组显示出最高的 IgM 滴度，这些值与 RPS 数据一致。此外，我们还确定鲑鱼气单胞菌的 A 层以非特异性方式结合免疫球蛋白 F(ab)'，干扰免疫测定和潜在的疫苗效力。我们的结果表明，疫苗设计会影响黑鮟鱇的免疫力，并为未来的黑鮟鱇疫苗计划提供指导。
