Long-term persistence of goblet cell hyperplasia after viral infection in wild-type and IFN-γ–null mice. (a) Wild-type and IFN-γ–null mice were inoculated with SeV (5,000 EID₅₀) or SeV-UV, and lung sections were stained for PAS and MUC5AC mucin as described in Figure 4 legend. Representative photomicrographs are shown for each genotype and condition (n = 5) at postinoculation day 365. Bar, 20 μm. (b) Quantification of results shown in a. Values represent mean ± SEM. The response of IFN-γ–null mice was no different from that of wild-type mice. *Significant change from control SeV-UV treatment.