Analysis of immune gene expression in infected and vaccinated rainbow trout Oncorhynchus mykiss with a focus on cytokines of adaptive immunity

The aquaculture sector is currently thriving, and has expanded to meet the demand for fish and shellfish as an alternative protein source to meat. This is especially true for high value products such as Atlantic salmon, where in Scotland salmon farming is reported to be worth> £1 billion to the national economy. Currently around 40% of farmed fish and shellfish destined for human consumption are derived from aquaculture. Therefore, a great deal of attention is paid to problems that the industry faces, with fish diseases of paramount importance. A variety of species of bacteria, viruses and parasites are common in the aquatic environment, which can result in serious diseases amongst fish stocks. As a result, ways to improve disease resistance have been the focus of much attention, with the use of vaccines considered a desirable way forward. However, other approaches are also followed, such as the use of immunostimulants to improve fish health in a more limited, non-specific way, or the use of genetic markers to allow selective breeding of important disease resistance traits. For all of these approaches more information is needed on the pathways that give rise to disease resistance in fish in different situations, to allow their manipulation or monitoring, and the studies in this thesis are directed towards this goal. Fish has been used as a model to study the evolution of vertebrate immunolity for some deacades, especially work on humoral immune responses where knowledge on antibody production has dominated much of the literature on fish immunology. In contrast, little known about specific cell-mediated immunity in fish, even though it also likely plays an important role in the immune system and disease resistance. Therefore, this thesis has been focused on analysing such responses, taking advantage of the recently discovered cytokines of adaptive immune responses in fish, which allow transcriptomic studies in particular to look at the molecules turned on during infection and after vaccination. Thus the goal of this thesis was to take advantage of some successful vaccines that exist for rainbow trout, and examine the gene expression changes that occur in vaccinated trout post-challenge with the homologus pathogen, and to try to dissect pathways that may correlate with disease resistance in this species.EThOS - Electronic Theses Online ServiceGBUnited Kingdo