Transcriptomic profiling of mink spleen infected by Aleutian mink disease virus: Insight into immune response

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, the spleen being one of the major targeted organs. Transcriptomics has been widely used to reveal genes and biological pathways and to 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 using transcriptomics. For this purpose, twelve AMDV-free black male mink (3 sets of 4 full-sibs) were housed for 4-7 days pre-inoculation and then were intranasally inoculated with viral homogenate and euthanized at 24 h (Day 1), 48 h (Day 2), and Day 7 post-infection. Spleen tissues were collected from infected and control (Day 0) mink for RNA isolation. Libraries were prepared (Illumina TruSeq™ RNA kit) and sequenced (HiScanSQ, 101 bp paired-end reads). After cleaning with Cutadapt v1.4.2, 942,803,540 high-quality reads remained for analysis. Differential gene expression analyses revealed that the highest number of significant differentially expressed (DE) genes were observed between Day 1 and Day 0 (168) while the fewest DE genes (23) were observed between Day 7 and Day 0. A total of 19 DE genes are identified between three observation pair comparisons and eight 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 lipid metabolism which are important mechanisms for the host 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 AMDV. 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 AMDV infections.