3.5 T-bet-dependent T-cell activation was found in wild boar but not domestic pigs

Expression of the T-box transcription factor TBX21 (T‑bet) in αβ and γδ T cells was investigated as a marker for activation. Domestic pigs had relatively high levels of T‑bet+ cells even before the infection and thus, there was no further activation measurable over the course of the study. In blood and spleen, T‑bet expression was decreased below baseline levels (Supplemental figure 2). In contrast, we detected increased frequencies of T‑bet+CD4/CD8α+ αβ T cells in spleen, lung, and liver of infected wild boar 10 dpi (Figure 6). Moreover, we found heightened proportions of T‑bet+CD4+/CD8α αβ T cells 10 dpi and of all differentiation states of γδ T cells 7 and 10 dpi in the lung of infected wild boar (Figure 6).