Do the Microbiota Influence Vaccines and Protective Immunity to Pathogens?

The gut-resident constituents of the microbiota protect the mucosa from invasive pathogens through engagement of both innate and adaptive branches of the immune system. They are also likely to provide systemic protection from pathogens, by enhancing host robustness and tolerance to the invasive microbes and by inducing immune responses that prevent their growth. These properties of commensal microbiota, particularly the capacity of some bacteria to induce diverse types of antigen-specific immune responses, raises the prospect that they could be deployed as vaccine vectors to generate effective local and systemic immunity to viral and bacterial pathogens.