This first transcript could fulfil the requirements of the rapid induction of the IFN system after infection, as shown by the quick phosphorylation of I-κB, one of the upstream signals of the IFN-β gene activation, which is observed as early as 5 minutes after virus entry [14], and by the NF-κB DNA binding activity detected within one hour [12]. Here, IFNB1 is linked to infection.