Reyes Miguel, Ramírez Cesar, Ñancucheo Ivan, Villegas Ricardo, Schaffeld Guillermo, Kriman Luis, Gonzalez Javier, Oyarzun Patricio
Bioinnovation Ltd, Providencia, Santiago 7501265, Chile.
Facultad de Ingeniería y Tecnología, Universidad San Sebastián, Lientur 1457, Concepción 4080871, Chile.
Vaccine. 2017 Jan 23;35(4):626-632. doi: 10.1016/j.vaccine.2016.12.013. Epub 2016 Dec 21.
DNA vaccination has emerged as a promising tool against infectious diseases of farmed fish. Oral delivery allows stress-free administration that is ideal for mass immunization and of paramount importance for infectious pancreatic necrosis (IPN) and other viral disease that affect young salmonids and cause economic losses in aquaculture worldwide.
We describe the development and in vivo assessment of an "in-feed" formulation strategy for oral immunization with liposomal DNA vaccines, by delivering a vaccine construct coding for an immunogenic region of the VP2 capsid protein. A challenge against IPNV was carried out to determine the vaccine efficacy, by comparing the mortality of pre-smolt Atlantic salmons immunized and non-immunized with the oral vaccine. The antibody response (ELISA) and hematological parameters after immunization were examined, as well as the vaccine effect on the growth and internal structures of fry salmons (histological analysis). The vaccine distribution in the experimental tank after oral administration was investigated by HPLC and PCR amplification.
The oral vaccine induced detectable levels of VP2-specific antibodies and conferred significant protection following IPNV challenge, with relative percent survivals (RPS) of 58.2%, for single dose (1mg/kg⋅d), and 66% for double dose (2mg/kg⋅d). We further provide evidence in favour of the vaccine safety to fish and demonstrated absence of pDNA in the tank water, but presence of vaccine residues in faeces and unconsumed feed sediments (solid wastes).
The delivery platform for liposomal DNA vaccination via feed was successfully proved against IPNV in Atlantic salmon, showing the oral vaccine to be immunogenic and safe for fish, and providing significant protection after oral administration. The "in-feed" technology for oral DNA vaccination holds potential to be applied against IPNV and other pathogens that currently threaten the aquaculture worldwide.
DNA疫苗已成为防治养殖鱼类传染病的一种有前景的工具。口服给药可实现无应激接种，这对于大规模免疫来说是理想的方式，对于传染性胰腺坏死病（IPN）以及其他影响幼鲑并在全球水产养殖中造成经济损失的病毒性疾病而言至关重要。
我们描述了一种用于口服脂质体DNA疫苗免疫的“饲料中添加”制剂策略的开发及体内评估，通过递送编码VP2衣壳蛋白免疫原性区域的疫苗构建体来实现。通过比较口服疫苗免疫和未免疫的前洄游期大西洋鲑的死亡率，对传染性胰腺坏死病毒（IPNV）进行攻毒以确定疫苗效力。检测免疫后的抗体反应（ELISA）和血液学参数，以及疫苗对鱼苗生长和内部结构的影响（组织学分析）。通过高效液相色谱（HPLC）和聚合酶链反应（PCR）扩增研究口服给药后疫苗在实验水箱中的分布情况。
口服疫苗诱导产生了可检测水平的VP2特异性抗体，并在IPNV攻毒后提供了显著保护，单剂量（1mg/kg·d）的相对存活率（RPS）为58.2%，双剂量（2mg/kg·d）为66%。我们进一步提供了疫苗对鱼类安全且水箱水中不存在质粒DNA（pDNA）的证据，但粪便和未消耗的饲料沉积物（固体废物）中存在疫苗残留。
通过饲料进行脂质体DNA疫苗接种的递送平台在大西洋鲑中成功证明对IPNV有效，表明口服疫苗对鱼类具有免疫原性且安全，并在口服给药后提供显著保护。用于口服DNA疫苗接种 的“饲料中添加”技术有潜力应用于防治IPNV和目前威胁全球水产养殖的其他病原体。
