Fig. 2

CD4⁺ T-cell proliferative responses to individual peptides within positive peptide pools. CD4⁺ T-cells (effector cells; 1 × 10⁵ cells/50 μl) from four BLV-infected cattle (S2, S4, R1, and N1) were co-incubated with mitomycin C-treated PBMCs (APCs; 4 × 10⁵ cells/50 μl) and incubated with either 80% DMSO (negative control) or peptide from pools 9, 11 and 14 (for S2), pool 21 (for S4), pools 20 and 21 (for R1), and pools 9 and 21 (for N1), all at a final concentration of 20 μM. The cells were incubated with peptide for 113 h at 37 °C and CD4⁺ T-cell proliferation was examined using Cell Counting Kit-8. The absorbance of the test wells was compared with that of control wells incubated without peptide and the Stimulation Index (SI) was calculated as follows: \( \mathrm{Stimulation}\ \mathrm{Index}\ \left(\mathrm{SI}\right)=\frac{\left[\mathrm{PBMC},\mathrm{CD}4,\mathrm{peptide}\right]-\left[\mathrm{Medium}\ \mathrm{only}\right]}{\left[\mathrm{PBMC},\mathrm{CD}4,\mathrm{DMSO}\right]-\left[\mathrm{Medium}\ \mathrm{only}\right]} \). The bars represent the mean ± standard deviation (SD) of triplicate wells. Asterisk and shade box bar mean the peptide showed significantly higher value than DMSO (negative control) well (p < 0.01)