Initial sequencing and tissue distribution of Toll-like receptor 3 mRNA in white-tailed deer (Odocoileus virginianus)

Toll-like receptor (TLR) 3 recognizes double-stranded RNA (dsRNA) and activates a signal transduction pathway that results in the release of a variety of chemokines and cytokines and apoptotic activity. Variability in TLR3 expression may play an important role in disease susceptibility of white-tailed deer (WTD; Odocoileus virginianus) to bluetongue and epizootic hemorrhagic disease viruses, which are dsRNA viruses. Because little is known about TLR3 in WTD, our objective was to sequence WTD TLR3 mRNA and to determine baseline levels of tissue expression. A 209-base pair sequence of TLR3 mRNA was obtained from WTD peripheral blood mononuclear cells. Dot blots confirmed that the sequence obtained was part of total WTD mRNA. Variable expression or ligand binding of TLR3 may contribute to observed susceptibility differences between populations of WTD, so the level of TLR3 in small intestine, skin, spleen, heart, cecum, rumen, lymph node, lung, kidney, and liver from WTD fawns (n=2) was analyzed using real-time reverse transcriptase-polymerase chain reaction. Tissue expression of TLR3 mRNA relative to the housekeeping gene beta-actin was highest in spleen, heart, skin, and lung.