200 Transcriptomics analyses of mink spleen infected by Aleutian Disease

Abstract Aleutian disease (AD) is one of the most challenging mink diseases that causes high mortality and affects several economically important traits. Aleutian mink disease virus (AMDV) targets multiple organs and among them, the spleen is one of the major targeted organs. Transcriptomics has been widely used to reveal genes and biological pathways and identify biomarkers for early detection or prevention of diseases. This study aimed to identify genes and pathways related to the host response to AD infection in the spleen via transcriptomic study. Twelve (3 sets of 4 full-sibs) AMDV-free black male mink were housed in the clean section of the animal housing facility at the AD Research Centre (Truro, NS, Canada) between 4 to 7 d before inoculation. Before inoculation, sampling, and euthanasia, animals were anesthetized. The viral inoculum was a 10% (W/V) passage 2 of AMDV prepared from the spleens of mink infected with a local strain and stored at − 80 °C. Animals were intranasally inoculated under sedation with 60 µL of the viral homogenate, corresponding to approximately 300 to 700 ID50. Infected mink were humanely euthanized and the spleen tissues were collected for RNA isolation at 24h (d 1), 48h (d 2), and d 7. Libraries were prepared from total RNA using the Illumina TruSeqTM RNA kit, and were sequenced using the HiScanSQ platform, producing 101 bp reads from each end. The raw RNA-Seq data were cleaned using Cutadapt V1.4.2 and after the cleaning process was completed, 942,803,540 paired-end reads remained to be used in downstream analysis. Differential gene expression analyses revealed most (168) significant differentially expressed (DE) genes between d 1 and d 0 (Control or ADMV-free mink) while fewer DE genes (23) were between d 7 and d 0 (Table 1; Figure 1). A total of 19 DE genes are identified between three pair comparisons and seven of them are directly involved in immune response (FGL2, TLF8, LRP1, SERPINB9, MSR1, C3, PLA2R1, and XCR1). Gene enrichment analyses revealed pathways related to innate immune and fat metabolism which are important for the host mechanism to fight against infections. One of the important pathways is neutrophil degranulation which functions as aiding in the elimination of pathogens and the initiation of the inflammatory process. In conclusion, the current study provides insight into the transcriptomic profiles of the spleen in mink infected with AD. Identified candidate genes might be used for functional studies or as prior information for markers or genomic selection against AD in mink. Further studies in other tissues or single-cell RNA sequencing might deliver more comprehensive pictures of host responses to AD infections.