Relative IFN-γ (A) or IL-4 (B) mRNA expression or IFN-γ/IL-4 ratio (C) following stimulation of BLN mononuclear cells of foals (striped bars) or adult horses (dotted bars) with recombinant R. equi VapA, VapC, VapD, VapE, VapF, VapG, or VapH. The results are displayed as means ± SD. *, statistically significant difference between results for foals and those for adult horses (P < 0.05).