VIP and infection: Infection of WT and Vip−/−del32 MEFs with either ZIKV strains MR766 or PRVABC59 revealed that at 48 h.p.i viperin expression was induced in the WT MEFs but not the Vip−/−del32 MEFs indicating that the innate cellular response to ZIKV infection is activated and results in viperin expression (Fig. 7A).