Ikke-klassiske MHC klasse I L-linjegener i atlantisk laks (Salmo salar) - Potensiell funksjonell rolle som tidlige antivirale varslingssignaler

Abstract

The Atlantic salmon farming industry is constantly growing in Norway and if managed properly can present a viable solution to the constantly increasing food demand resulting from staggering human population growth. However, one of the main challenges the industry is facing are re- curring fish viral disease outbreaks. Fish vaccination strategies, especially with multicompo- nent vaccines, is used routinely as a prophylactic measure, but present-day fish vaccines do not prevent viral disease outbreaks. To better understand why the effect of today’s virus vaccines is sub-optimal and how the vaccines can be improved, the fish's cellular immune response must be studied in more detail. As virus are obligate intracellular organisms residing inside the host cells, the key to combating them lies within the T cell mediated arm of the immune response. For activation of T cells, antigens are displayed on special complexes encoded by Major His- tocompability Complex (MHC) genes. MHC genes are sub-divided into classical and non-clas- sical genes. Salmonids have a large repertoire of non-classical MHC class I genes, divided into 6 lineages. Among these the L-lineage genes have emerged as potential early warning mole- cules that are rapidly induced in response to both viral infections and type I interferon signaling. This work focuses on two MHC class I L lineage genes, LIA and LGA. Here, using Chinook Salmon Embryo-214 (CHSE)-cells that are derived from Chinook salmon (Oncorhynchus tshawytsha) it was shown that LIA, similarly to what has been observed in Atlantic salmon is upregulated in response to interferon stimulation and following SAV3 infection in vivo. This reinforces a putative role of LIA in salmonid anti-viral immunity and hints at an important, evolutionary conserved biological role. Further, Chinook Salmon Embryo-214 (CHSE)-cells overexpressing Sasa-LGA were established. Protein isolation of membrane and cytosol proteins from the cells, respectively, was performed, and subsequent western blots with tag specific antibodies, showed that Sasa-LGA was predominantly found in the membrane fraction, rein- forcing the hypothesis that these complexes have an antigen-presenting role. These cell lines will be invaluable tools to further elucidate the functional roles of LGA and aid in the identifi- cation of potential LGA-ligands.