Bovine humoral response towards rFhTSP2 over the course of the trial. (a) Serum IgG, (b) serum IgA, and (c) saliva IgA responses from Day 0 (pre-vaccination), Day 42 (post-vaccination), Day 84 (post-challenge), and Day 125 (end of trial) from Group 1 (G1: dark grey) subcutaneously vaccinated with PBS; Group 2 (G2: red) intranasally vaccinated with rLTB-FhTSP2; and Group 3 (G3: blue) subcutaneously vaccinated with rFhTSP2. Each animal within a group is represented by a different shape. The reactivity of 5 μg/mL of rFhTSP2 was analysed using serum (diluted 1:50) or saliva (diluted 1:8) and an anti-bovine IgG HRP secondary antibody diluted 1:5000 or a anti-bovine IgA HRP antibody diluted 1:2000. The mean OD of each group is represented by a solid line. Significant differences (p < 0.05) of the mean are denoted by asterisks (*).