Development of a mucosal adjuvant for fish vaccination

水产养殖是为不断增长的世界人口提供食物的增长最快的部门之一。全世界人类消费的鱼类中，约有50%来自水产养殖，预计这一数字将进一步上升。与其他食品生产部门一样，水产养殖业的可持续性依赖于对鱼类健康的良好管理和对疾病的有效控制。传染病的爆发可能导致严重的经济损失，可能需要多年才能恢复。在过去的30年里，疫苗接种已成为提高鱼类对细菌抵抗力的重要手段，并大大减少了鱼类养殖中抗生素和有毒化学品的使用，在该行业的环境影响以及改善鱼类健康方面带来了巨大的好处。实现针对疾病的保护的最有效的方式是通过腹膜内注射施用疫苗，部分原因是抗原可以通过添加用于激活免疫系统的油基佐剂而缓慢释放。尽管有上级保护，但这种方法对鱼造成压力，劳动强度大，并且可能引起不希望的副作用，如腹膜粘连、肉芽肿甚至自身免疫。然而，浸入式疫苗接种，其中鱼被简单地放置在稀释的疫苗溶液中，已被证明在鱼中起作用，但迄今为止仅限于几种细菌病原体，并且通常需要加强剂才能完全保护，限制了其使用。对有效佐剂的需求在很大程度上推动了注射疫苗接种，并且随着正在开发用于哺乳动物/人类的几种高效粘膜佐剂的出现，需要重新审视这一点。通过将牛津大学的世界领先的粘膜佐剂组和阿伯丁的世界领先的鱼类免疫学组联系起来，该提案计划优化由Sattentau教授开发的用于鱼类的新型粘膜佐剂的使用。最初，我们将制备含有灭活细菌病原体（鲁氏耶尔森氏菌）的稳定制剂，适用于在鱼类中进行测试。我们将使用三种佐剂用量不同的制剂，并将在鱼（虹鳟鱼）中引起的反应与商业浸没疫苗引起的反应进行比较。我们将研究增强许多重要免疫基因表达的能力，这些基因被认为参与保护性反应，以及血液抗体水平。我们将根据引发的反应选择最佳制剂，用于进一步的实验，其中鱼将接种疫苗，然后暴露于活病原体，以观察反应是否提供良好的保护/免疫力。如果成功的话，这些结果将有可能彻底改变鱼类的浸入式疫苗接种。用有效的粘膜佐剂获得的增强的免疫应答/保护可以避免在浸泡疫苗接种后需要加强疫苗接种，或者允许对目前需要佐剂IP注射疫苗接种的疾病诱导保护性应答。我们相信，这种方法有能力在鱼的浸泡（粘膜）接种技术的一个步骤的变化。

Aquaculture is one of the fastest growing sectors that provide food to the expanding world population. Already ~50% of fish consumed by humans worldwide is produced in aquaculture, and this figure is projected to rise further. Like other food producing sectors, the sustainability of the aquaculture industry relies on good management of fish health and effective control of diseases. Outbreaks of infectious diseases can lead to heavy economic losses which may require many years to recover. During the last 30 years, vaccination has become an important means to improve fish resistance to bacteria, and has allowed a significant reduction in the use of antibiotics and toxic chemicals in fish farming, with tremendous benefits in terms of the environmental impact of the industry as well as improved fish health. The most effective way to achieve protection against diseases is to administer vaccines via intraperitoneal injection, partly due to the fact that antigens can be slowly released with the addition of oil based adjuvants for activation of the immune system. Despite the superior protection, this method causes stress to the fish, is labour intensive and can induce unwanted side-effects such as peritoneal adhesions, granulomas and even autoimmunity. However, immersion vaccination, where the fish are simply placed into a solution of diluted vaccine, has been shown to work in fish but to date is limited to a couple of bacterial pathogens and typically requires boosters for full protection, limiting its use. The need for effective adjuvants has largely driven injection vaccination, and this needs to be revisited with the appearance of several highly efficacious mucosal adjuvants being developed for use in mammals/humans. By linking a world leading mucosal adjuvant group at Oxford and a world leading fish immunology group at Aberdeen, this proposal plans to optimise the use of a novel mucosal adjuvant for use in fish, that has been developed by Professor Sattentau. Initially we will prepare stable formulations containing a killed bacterial pathogen (Yersinia ruckeri), that are suitable for testing in fish. We will use three formulations that vary in terms of the amount of adjuvant being used, and will compare the responses elicited in the fish (rainbow trout) with those elicited by a commercial immersion vaccine to this disease. We will examine the ability to enhance the expression of a number of important immune genes, thought to be involved in protective responses, as well as blood antibody levels. We will select the best formulation in terms of the responses elicited, to be used in a further experiment where the fish will be vaccinated and then exposed to the live pathogen, to see if the responses give good protection/immunity. If successful the results would have the potential to revolutionise immersion vaccination of fish. Enhanced immune responses/protection obtained with effective mucosal adjuvants may avoid the need for booster vaccination following immersion vaccination, or allow protective responses to be induced to diseases that currently require adjuvanted IP injection vaccination. We believe such an approach has the capacity for a step change in immersion (mucosal) vaccination technology for fish.