PSXII-9 - Identifying selection signatures for immune response and resilience to Aleutian disease in mink using genotypes data

Abstract: Aleutian disease (AD), a severe immune-complex disease, brings tremendous financial losses to the mink industry. Resilience is an animal's ability to minimize the influences caused by disturbances and maintain its performance under pathogen exposure. Many AD-positive farms have selected AD-resilient mink based on AD tests and/or AD-resilience indicator traits, such as growth, pelt quality, and reproduction. Selection based on these indicator traits may have changed the patterns of genetic variation and potentially represent a genomic signature that can be used to identify genes subjected to selection. Therefore, the main objective of this study was to identify the selection signatures related to immune response (IRE) and resilience to AD. . A total of 1,411 mink in five color types (black, demi, mahogany, pastel, and stardust) from the Canadian Centre for Fur Animal Research (Truro, Nova Scotia, Canada), which is an AD-positive facility, were genotyped using the Axiom Affymetrix Mink 70K single nucleotide polymorphism (SNP) panel. For the IRE trait, 264 mink were grouped into pairwise groups based on the combined results of counter-immunoelectrophoresis (CIEP) and enzyme-linked immunosorbent assay (ELISA) tests. Individuals in black (n=29), demi (n=131), mahogany (n=76), and pastel (36) color types were also grouped based on combined results of CIEP and ELISA tests, respectively. For resilience traits, two methods were used to group CIEP-positive individuals into pairwise groups: 1) based on their general resilience performance (GRP, n=30), which was measured by considering individual performance for feed conversion ratio, Kleiber ratio, and pelt quality, and 2) based on female reproductive performance (FRP, CIEP-positive dams only, n=36), which was measured by the number of kits alive 24h after birth. The pairwise fixation index, nucleotide diversity, and cross-population extended haplotype homozygosity were used to detect selection signatures. Only SNPs detected by at least two methods were considered selection signatures candidates, including 619, 569, and 526 SNPs for IRE, GRP, and FRP traits, respectively. The genes annotated from the candidate SNPs were associated with previously reported traits influenced by AD, including immune system process, growth, reproduction, and pigmentation. Notably, two olfactory-related gene ontology (GO) terms were significant (q < 0.05) for all studied traits, suggesting AD might cause loss of smell in infected mink. Additionally, the differences in genes and GO terms detected across different color types for IRE indicated that mink of different color types may differ in immune response to AD. The mitogen‑activated protein kinase (MAPK) signalling pathway was significant (q < 0.05) in Kyoto Encyclopedia of Genes and Genomes pathway analyses for FRP, indicating AD infection may disorder the MAPK signalling pathway, in turn influencing female reproductive performance. Our study has enhanced the understanding of genomic architecture underlying resilience of mink to AD and sheds light on the underlying biological mechanisms involved.