IFNL1 and infection: Increased expression of IFNK and IFNL1 interferon transcripts during infection suggested that combined type I and type III interferon signaling mediates the innate response (exemplified by the interferon-induced protein with tetratricopeptide repeats 1 gene IFIT1, a canonical interferon-stimulated gene) and APOBEC3A transcript expression (Fig. 1A and fig.