Thus, in the ileum with PPs, where villi responded to γ-PGA and induced IFN-β expression, level of TLR4 remained unchanged although expression of other TLRs was differentially affected by norovirus infection. It remains to be determined whether γ-PGA’s antiviral activity against norovirus was potentiated by the amplification of TLR4 signaling through sensitization of other upregulated TLRs in the ileum upon norovirus infection.