In contrast, we have previously shown that IRF3/7-/- mice infected s.c. in the foot with CHIKV (i) had high viraemias, ≈107−1010 CCID50/ml, about 4 logs higher than in wild-type mice between days 3–5 post infection, (ii) showed hemorrhagic symptoms (i.e. edematous foot swelling, hypothermia, oliguria) [6] and (iii) developed hypovolemic shock requiring euthanasia [6]. This evidence concerns the gene IRF3 and infection.