Bacterial residents of the gut boost immune responses to vaccination in mice.

Humans vaccinated against the influenza virus ramp up expression of a protein called TLR5, which is involved in detecting certain types of bacterium. To see how this protein and gut bacteria might affect immune responses to vaccines, Bali Pulendran of Emory University in Atlanta, Georgia, and his colleagues studied mice that lack the gene encoding TLR5.

They found that the animals produced fewer antibodies in response to flu vaccination than normal mice. The team saw similar effects in mice reared in a germ-free environment and in those treated with powerful antibiotics. Antibody responses could be restored, however, by inoculating the mice with the kind of bacteria to which TLR5 is sensitive.

The results suggest that antibiotic treatment could hinder the effects of certain vaccines, the authors say.

Immunity http://doi.org/vm3 (2014)