IFNL3 and infection: Figure 2a shows that the viral titers of wtCSFV and ∆Npro were significantly reduced by IFN-λ3 treatment, particularly from 24 to 48 hpi. IFN-λ3 inhibited wtCSFV and ∆Npro in a dose-dependent manner: the higher the concentration of IFN-λ3, the stronger the inhibition of viral replication with 1.5 to over 2 log decrease of the virus titers at 1000 ng/mL treatment (Figure 2b). Figure 2c indicates that IFN-λ3 inhibited CSFV replication when applied before, during or after infection, while the highest level of inhibition was seen when applied before infection.