STAT1 and infection: The protective activity of ribavirin was then examined in CCHFV-infected suckling mice [13], signal transducer and activator of transcription-1 (STAT-1) knockout mice [14] and type I interferon receptor deficient (IFNAR−/−) mice [18,19], which suggested that ribavirin treatment against CCHFV must be started soon after infection to see clinical benefit.