Background
In adult rats, initial exposure to antigens by a mucosal route triggers tolerance such that any subsequent re-exposure, even by a systemic route,
Significance
This work demonstrates that newborns may be uniquely qualified to prevent induction of mucosal tolerance to oral antigens. These results should be further explored to establish whether prevention of tolerance by early life oral vaccination can be exploited to prime for mucosal as well as systemic immunity and thus protect this susceptible population against infectious diseases.