School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024, China.
School of Life Science and Biotechnology, Dalian University of Technology, Dalian, 116024, China; Center for Food Safety of Animal Origin, Ministry of Education, Dalian University of Technology, Dalian, 116600, China.
Fish Shellfish Immunol. 2019 Jan;84:108-119. doi: 10.1016/j.fsi.2018.09.073. Epub 2018 Sep 26.
Skin ulceration syndrome in sea cucumbers is an infectious bacterial disease with fast and high mortality. This study investigated the protection of chicken egg yolk antibodies (IgY) on skin ulcer syndrome in sea cucumbers induced by intraperitoneally injecting Shewanella marisflavi AP629. Inactivated whole S. marisflavi AP629 cells were used as an immunogen to immunize laying hens. The highest titer of the obtained specific IgY by ELISA was 1:90000. Specific IgY significantly inhibited the growth of S. marisflavi AP629 in a liquid medium, dose-dependent manner at concentrations ranging from 0.5 to 2 mg/mL. Results obtained from scanning electron microscopy and confocal laser scanning microscopy showed that specific IgY could make bacteria agglutinate and damage the cell membrane of S. marisflavi AP629, resulting in a decrease of bacterial viability. Sea cucumbers treated with 25, 5, and 1 mg/mL anti-S. marisflavi AP629 IgY could achieve survival rates of 77.5%, 50%, and 22.5% at day 12 when the infection and injection therapy were carried out at the same time, respectively. However, survival rates of sea cucumbers treated with 25 mg/mL of nonspecific IgY were only 7.5% at day 12. All sea cucumbers in the positive control group died within twelve days after bacterial inoculation. Levels of the five humoral immune factors (LYZ, ACP, NOS, SOD, CAT) released by coelomocytes were significantly increased in the specific IgY group compared to the nonspecific IgY and positive control groups within 12 h. However, the activities of LYZ, ACP, and SOD decreased rapidly at the 48 h time point in the specific IgY group, indicating that specific IgY treatment could shorten the time needed to restore balance in sea cucumber immune systems. Oral prophylaxis with egg yolk powders was that all sea cucumbers were challenged with 4.2 × 10 CFU S. marisflavi AP629 by intraperitoneal injection after 60 days of feeding. Survival rates of diets containing 10%, 5%, and 1% specific egg yolk powder were 57.5%, 52.5%, and 30% by day 12, respectively, and the survival rate was 27.5% for the nonspecific group and 22.5% for the positive control group. After feeding for 60 days, enzyme activities of LZY, NOS, and SOD were all significantly enhanced in sea cucumbers fed with specific egg yolk powder when compared to the control group (p < 0.05). This study demonstrated that the phagocytic activities of coelomocytes were significantly stimulated after specific IgY treatment over that of nonspecific IgY or without IgY treatments in sea cucumbers (p < 0.05). Overall, our results revealed that anti-S. marisflavi AP629 IgY has a positive immunomodulatory effect on sea cucumbers infected with S. marisflavi AP629.
海胆皮肤溃疡综合征是一种具有高死亡率的传染性细菌性疾病。本研究探讨了鸡卵黄抗体（IgY）对经腹腔注射希瓦氏菌 AP629 诱导的海胆皮肤溃疡综合征的保护作用。用灭活的全希瓦氏菌 AP629 细胞作为免疫原免疫产蛋母鸡。通过 ELISA 获得的特异性 IgY 的最高效价为 1:90000。特异性 IgY 以浓度依赖的方式在 0.5 至 2mg/mL 的范围内显著抑制了液体培养基中希瓦氏菌 AP629 的生长。扫描电子显微镜和共聚焦激光扫描显微镜的结果表明，特异性 IgY 可使细菌聚集并破坏希瓦氏菌 AP629 的细胞膜，导致细菌活力下降。当同时进行感染和注射治疗时，用 25、5 和 1mg/mL 抗希瓦氏菌 AP629 IgY 处理的海胆在第 12 天的存活率分别为 77.5%、50%和 22.5%。然而，用 25mg/mL 非特异性 IgY 处理的海胆在第 12 天的存活率仅为 7.5%。所有接种细菌的阳性对照组海胆在 12 天内死亡。与非特异性 IgY 和阳性对照组相比，特异性 IgY 组的腔细胞释放的五种体液免疫因子（LYZ、ACP、NOS、SOD、CAT）水平在 12 小时内显著升高。然而，在特异性 IgY 组中，LYZ、ACP 和 SOD 的活性在 48 小时时迅速下降，表明特异性 IgY 治疗可以缩短海胆免疫系统恢复平衡所需的时间。蛋黄粉的口服预防是在 60 天喂养后，通过腹腔注射向所有海胆中注入 4.2×10 CFU 希瓦氏菌 AP629。含有 10%、5%和 1%特异性蛋黄粉的饮食的存活率分别在第 12 天达到 57.5%、52.5%和 30%，而非特异性组的存活率为 27.5%，阳性对照组的存活率为 22.5%。60 天后，与对照组相比，饲喂特异性蛋黄粉的海胆的 LZY、NOS 和 SOD 酶活性均显著增强（p<0.05）。本研究表明，特异性 IgY 处理后，海胆的吞噬活性明显高于非特异性 IgY 或无 IgY 处理（p<0.05）。总的来说，我们的研究结果表明，抗希瓦氏菌 AP629 IgY 对感染希瓦氏菌 AP629 的海胆具有积极的免疫调节作用。
