|FERNANDO, SAMODHA - University Of Nebraska|
|Wells, James - Jim|
Submitted to: International Society for Animal Genetics (ISAG)
Publication Type: Abstract Only
Publication Acceptance Date: 5/17/2019
Publication Date: N/A
Technical Abstract: Abscess is the highest cause for liver condemnation and is estimated to cost the industry $64 million annually. Fusobacterium necrophorum, commonly found on the rumen wall, is the primary bacteria associated with liver abscess. Theoretically, damage to the rumen wall allows ruminal bacteria to travel to and colonize in the liver. The objective of this study was to determine whether there were gene expression differences in the rumen epithelium of beef cattle with severe liver abscesses compared to those with no liver abscess. Rumen tissue was collected from 31 steers and heifers with liver abscess and 31 animals with no liver abscess. Total RNA was isolated from the tissue and stranded mRNA libraries were generated and sequenced. An average of 42 million reads per library were obtained and 98% of the reads mapped to the ARS-UCD1.2 bovine genome assembly. Differentially expressed genes (DEG) were identified using DESeq2 with a 2x2 factorial design. A sex effect was identified with 4,313 genes identified as differentially expressed between steers and heifers. A total of 310 genes were identified as differentially expressed between animals with severe liver abscess and those without, and 212 genes were differentially expressed in the sex by abscess interaction analysis. The list of liver abscess DEG was subjected to the Database for Annotation and Visualization and Integrated Discovery (DAVID) v6.8 to identify genes that were over-represented in biological functions and pathways. Genes belonging to the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-KB) signaling (LY96, RELB, TRIM25, LOC524810) and Epstein-Barr virus infection (TYK2, RELB, LOC524810) pathways were identified, suggesting that the animals with liver abscess were experiencing or responding to infection. Both pathways induce inflammatory cytokine responses. The expression of the genes identified in this study or downstream cytokine responses may serve as a method to monitor whether animals have existing liver abscesses or predict those that are more likely to develop liver abscesses.