Figure 2: The PTSL vaccine elicited Th1 type cell-mediated immune responses (i.e. T cells expressing IL-2, IFN-γ and TNF-α) in piglets.

PBMCs were isolated from five piglets of the control, PO and IM groups on the 29th day post vaccination (dpv), and were stimulated with inactivated S. Choleraesuis antigen in vitro. RNA was extracted for determination of IL-2, IL-4, IL-12, IFN-γ and TNF-α expression levels by RT-PCR. The results are presented as fold of expression in unstimulated control cells from each animal. *p < 0.05; **p < 0.01.