While IL-27 remained unchanged in the serum of infected C57BL/6 mice, infected BALB/c showed an early increase that was significant 4 days after infection (p ≤ 0.05) and always higher than the IL-27 levels of C57BL/6 mice (p ≤ 0.05 comparing the day 2 and p ≤ 0.01 the day 4 after infection) (Figure 1B). This evidence concerns the gene IL27 and infection.