In particular, the TLR-5-mediated sensing of flagellin derived from the gut microbiota was shown to affect the antibody response in influenza and inactivated polio vaccines [149]; Trl5−/−, antibiotic-treated, and GF mice were not able to produce influenza-specific IgG and IgM production as efficiently as WT mice in the context of vaccination. This evidence concerns the gene CD40LG and influenza.