Understanding the intracellular lifestyle of F. piscicida and the role of host immune responses are of vital importance to development of efficient prophylactics. The current knowledge is limited and this project aims at filling some gaps in this field.
Host-pathogen interactions will be examined by performing in vitro studies with our unique cod cell line and primary macrophages. We will establish invasion assays to study internalisation and the level of intracellular replication. Further, this assay will be used to examine whether infection is dependent on temperature and study adherence and uptake of bacteria into cells.
The localisation of infection has implication for vaccine development and we aim to identify if F. piscicida reside within vesicles or in cytosol. We will perform basic structural studies of F. piscicida LPS and study the immune response to LPS. We will also study aspects of immunity that are known to play a role in infection with intracellular bacteria.
The main macrophage activating factor IFNg will be produced recombinant and its role in postponement of infection will be addressed, while studies of IL-1b secretion will reveal its role as a signalling cytokine of infection. Humoral immunity has been suggested to take part in eradication of intracellular bacteria mediated through antibody opsonisation that facilitate uptake in cells. We aim to study if this is present in cod.
Cell mediated immunity has been proposed as most important in intracellular infections and herein we will identify the T cell subtype that is activated by F. piscicida. Finally, we want to establish the RNAi technology to gain functional knowledge of important proteins in the immune defense against F. piscicida. Together, these studies will provide vital knowledge of the intracellular lifestyle of F. piscicida and cod immune responses.