IFNL1 and infection: At 24 and 48 h post-infection, the predominant interferons induced in the primary airway cells at the mRNA level were IFNβ, IFNL1, and IFNL2/IFNL3 (qRT-PCR cannot distinguish these isoforms), with IFNL1 and IFNL2/3 being the most upregulated (Figure 1A).