At day 3 post-infection, the IFN-γ mRNA expressions in group IV (p < 0.01) and group III (p < 0.05) were different compared with the expression level in group I. The IFN-γ mRNA expression in group IV was different (p < 0.05) compared with the expression level in group I at day 5 post-infection. This evidence concerns the gene IFNG and infection.