CD4 and infection: We did not detect statistically significant differences between the groups four weeks after vaccination (D28) or four weeks after challenge infection (D56) for the percentage of cytokine-producing CD4+ or TNF-α+ CD8+ T cells (data not shown), but the percentage of IFN-γ+, TNF-α+IFN-γ+ or IL-17A+ CD8+ T cells differed significantly after vaccination and/or challenge infection (Figure 6).