Induction of IFN-β expression by γ-PGA and MNV in mouse ileum. (a) Experimental schemes for ex vivo stimulation of the ileum with γ-PGA. (b) Mouse (n = 4) ileum with or without PPs was treated with γ-PGA ex vivo. After 18 h incubation, IFN-β mRNA levels in the ileal compartments depicted in (a) were determined by RT-qPCR. *P < 0.05; **P < 0.01; ***P < 0.001; n.s., not significant; by two-tailed unpaired Student’s t-test. (c) Microscopic analysis of TLR4-expressing cells in the ileum with or without PPs. Intestinal microvilli stained with a villin-specific antibody. (d) Microscopic analysis of the entry of MNV. Mouse ileum with or without PPs was infected with Qdot fluorophore-tagged MNV ex vivo in serum-free DMEM. At 2 h post-infection, cryosection images were taken after extensively washing the infected tissues. Scale bar, 50 μm.