Using CRISPR-edited human intestinal epithelial cell lines deficient in IFNλ1 or IFNλ2/3, we demonstrate that basal IFNλ2/3, but not IFNλ1, is essential for restricting infection by a broad range of viral pathogens, including rotavirus (RV), mammalian reovirus (MRV), vesicular stomatitis virus (VSV), and vaccinia virus (VV). This evidence concerns the gene IFNL1 and infection.