Munang'andu Hetron Mweemba
Section of Aquatic Medicine and Nutrition, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Ullevålsveien 72, P.O. Box 8146, Dep NO-0033, 046 Oslo, Norway.
Microorganisms. 2018 Apr 22;6(2):33. doi: 10.3390/microorganisms6020033.
Aquaculture is one of the most rapidly expanding farming systems in the world. Its rapid expansion has brought with it several pathogens infecting different fish species. As a result, there has been a corresponding expansion in vaccine development to cope with the increasing number of infectious diseases in aquaculture. The success of vaccine development for bacterial diseases in aquaculture is largely attributed to empirical vaccine designs based on inactivation of whole cell (WCI) bacteria vaccines. However, an upcoming challenge in vaccine design is the increase of intracellular bacterial pathogens that are not responsive to WCI vaccines. Intracellular bacterial vaccines evoke cellular mediated immune (CMI) responses that “kill” and eliminate infected cells, unlike WCI vaccines that induce humoral immune responses whose protective mechanism is neutralization of extracellular replicating pathogens by antibodies. In this synopsis, I provide an overview of the intracellular bacterial pathogens infecting different fish species in aquaculture, outlining their mechanisms of invasion, replication, and survival intracellularly based on existing data. I also bring into perspective the current state of CMI understanding in fish together with its potential application in vaccine development. Further, I highlight the immunological pitfalls that have derailed our ability to produce protective vaccines against intracellular pathogens for finfish. Overall, the synopsis put forth herein advocates for a shift in vaccine design to include CMI-based vaccines against intracellular pathogens currently adversely affecting the aquaculture industry.
水产养殖是世界上发展最为迅速的养殖系统之一。其快速扩张带来了多种感染不同鱼类的病原体。因此，为应对水产养殖中日益增多的传染病，疫苗研发也相应地有所扩展。水产养殖中细菌性疾病疫苗研发的成功很大程度上归功于基于全细胞灭活（WCI）细菌疫苗的经验性疫苗设计。然而，疫苗设计中一个新出现的挑战是细胞内细菌性病原体的增加，这些病原体对WCI疫苗无反应。细胞内细菌疫苗引发细胞介导免疫（CMI）反应，“杀死”并清除受感染细胞，这与诱导体液免疫反应的WCI疫苗不同，后者的保护机制是通过抗体中和细胞外复制的病原体。在本综述中，我概述了感染水产养殖中不同鱼类的细胞内细菌性病原体，根据现有数据概述它们的入侵、复制和细胞内存活机制。我还阐述了目前鱼类CMI的了解现状及其在疫苗研发中的潜在应用。此外，我强调了那些阻碍我们生产针对硬骨鱼类细胞内病原体的保护性疫苗的免疫学缺陷。总体而言，本文提出的综述主张在疫苗设计上做出转变，纳入针对目前对水产养殖业产生不利影响的细胞内病原体的基于CMI的疫苗。
