Tumor necrosis factor-alpha expression in white-tailed deer (Odocoileus virginianus) infected with Epizootic haemorrhagic disease virus

Epizootic haemorrhagic disease (EHD) is the most important infectious disease of white-tailed deer (WTD), however little is known about the role of inflammatory mediators in the pathogenesis. We characterized the expression of tumor necrosis factor-alpha (TNF-a) ex vivo in tissues of WTD experimentally or naturally infected with EHD virus serotype 2 and in WTD peripheral blood mononuclear cells (PBMC) infected with EHD virus serotype 2 in vitro. Circulating levels of TNF-a were evaluated in serum from experimentally infected deer via cytotoxicity assay. The expression of TNF-a in tissues was evaluated via immunohistochemistry (IHC) in both experimentally and naturally infected deer. Semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) was used to assess the level of TNF-a mRNA in tissues from experimentally infected deer and WTD's PBMC. Circulating levels of TNF-a were not increased in infected animals and TNF-a was not detected in tissues of infected deer. Increased transcription of TNF-a was detected neither in infected WTD nor in the PBMC. Tumor necrosis factor-alpha may not play a significant role in the pathogenesis of EHD virus infection in WTD.