While B. abortus infection did lead to activation of γδ T cells (and NK cells to a lesser extent), this effect was independent of TNF-α at 4 and 7 days post-infection, as mice neutralized of TNF-α in vivo still displayed enhanced CD69 expression by their γδ T cells and, in fact, more so than mice simply subjected to B. abortus infection (Figure 4E and data not shown). This evidence concerns the gene TNF and infection.