However, Pijlman et al. [82] was the first to characterize a host 5′- 3′ exoribonuclease 1 (XRN1) degrading the viral genomic RNA and, consequently, potentially generating sfRNAs (from the 3′ UTR) during West Nile, yellow fever and dengue virus infections. Here, XRN1 is linked to viral infectious disease.