Flagellin is a Th1 polarizing factor for human CD4 T cells and induces protection in a murine neonatal vaccination model of rotavirus infection.

Neonates have an increased susceptibility to infections, particularly those caused by intracellular pathogens, leading to high morbidity and mortality rates. This is partly because of a poor response of neonatal CD4 T cells, leading to deficient antibody production and a low production of IFN-γ, resulting in deficient elimination of intracellular pathogens. The poor memory response of human neonates has underpinned the need for improving vaccine formulations.