Center of Excellence in Fish Infectious Diseases (CE FID), Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
Biochemistry Unit, Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
Fish Shellfish Immunol. 2022 Aug;127:633-646. doi: 10.1016/j.fsi.2022.06.059. Epub 2022 Jun 30.
Columnaris is a bacterial disease, found in freshwater fish, caused by Flavobacterium oreochromis. The disease has a devastating impact on a range of cultured and wild freshwater fish species e.g. Lates calcarifer (Asian sea bass), which is a serious economic losses to the freshwater aquaculture in Thailand. The disease can be prevented by an efficacious vaccine, however, no licensed effective vaccine is available to date. Current study was based on the development of a novel mucoadhesive nano-encapsulated vaccine (EncapFlavoNP), where, cationic lipid-based nanoparticles were combined with an antigen obtained from F. oreochromis. Various parameters including transmission electron microscopy (TEM), physiochemical properties; zeta potential, and polydispersity index were determined. The TEM results depicted well-formed circular-shaped nano-encapsulates complexed with cationic lipid surfactants. The average diameter of the molecules was 200 nm, having a zeta potential of 31.82 mV, while, the polydispersity index (PDI) was 0.31. The in vivo study lasted for 8 weeks, the immunologic and protective potentials of the prepared molecules were determined by challenging the fish for 8 weeks. The most effective dilutions of EncapFlavoNP solution were 1:100 and 1:200, which significantly improved the efficacy of the immunity by increasing the level of antibody specific to F. oreochromis. A trend of upregulation was found in the immune-related genes including immunoglobulin M heavy chain (IgM), major histocompatibility complex class IIα molecules (MHC-IIα), and dendritic cell specific transcript (DCs) in gills, skin, liver, peripheral blood lymphocytes (PBLs), head kidneys, and spleen as compared to the control group (P < 0.05 and P < 0.01). Upon immunization with EncapFlavoNP solution at the dilution of 1:100 and 1:200, the significant increase in survival rate (SR) and relative percent survival (RPS) were found in fish challenged with virulent F. oreochromis bacterium (SR 72.50% and RPS 62.07) and (SR 65.83% and RPS 52.87), respectively as compared to the control group (P < 0.05). It can be concluded that immunization with EncapFlavoNP solution has significant immunologic and protective effects against Columnaris disease. Furthermore, the prepared vaccine candidate has more potential as compared to whole-cell immersion vaccination (FK-WC). It can be used on a large scale in the freshwater aquaculture industry to boost immunity against Columnaris disease.
柱状屈挠杆菌是一种细菌性疾病，存在于淡水鱼类中，由屈挠杆菌引起。该疾病对多种养殖和野生淡水鱼类物种造成严重破坏，例如尖吻鲈（亚洲海鲈），这给泰国淡水养殖业带来了严重的经济损失。该疾病可以通过有效的疫苗来预防，但是，目前还没有获得许可的有效疫苗。目前的研究基于开发一种新型的粘膜粘附纳米包封疫苗（EncapFlavoNP），其中阳离子脂质纳米颗粒与从屈挠杆菌获得的抗原结合。确定了各种参数，包括透射电子显微镜（TEM）、物理化学性质；zeta 电位和多分散指数。TEM 结果描绘了与阳离子脂质表面活性剂形成的良好圆形纳米封装复合物。分子的平均直径为 200nm，zeta 电位为 31.82mV，而多分散指数（PDI）为 0.31。体内研究持续了 8 周，通过对鱼类进行 8 周的挑战来确定制备分子的免疫和保护潜力。EncapFlavoNP 溶液的最有效稀释度为 1:100 和 1:200，这显著提高了免疫力，增加了针对屈挠杆菌的抗体水平。与对照组相比，在鳃、皮肤、肝脏、外周血淋巴细胞（PBLs）、头肾和脾脏中，免疫相关基因包括免疫球蛋白 M 重链（IgM）、主要组织相容性复合体 IIα 分子（MHC-IIα）和树突状细胞特异性转录物（DCs）的表达呈上调趋势（P<0.05 和 P<0.01）。用 EncapFlavoNP 溶液在 1:100 和 1:200 的稀释度下免疫，在受到毒性屈挠杆菌细菌攻击时，鱼类的存活率（SR）和相对存活率（RPS）显著增加（SR 为 72.50%，RPS 为 62.07%）和（SR 为 65.83%，RPS 为 52.87%），与对照组相比（P<0.05）。可以得出结论，用 EncapFlavoNP 溶液免疫对柱状屈挠杆菌病具有显著的免疫和保护作用。此外，与全细胞浸泡免疫（FK-WC）相比，该候选疫苗具有更大的潜力。它可以在淡水养殖业中大规模使用，以增强对柱状屈挠杆菌病的免疫力。
