The influence of the gut microbiota on influenza vaccine-induced immunity

Currently, annual vaccination is widely considered the most effective method for preventing and controlling influenza virus infection. However, many individuals mount suboptimal immune responses to vaccination and the factors leading to poor immune responses are yet to be elucidated. Interestingly, it has been proposed that microorganisms that inhabit the intestinal tract, the gut microbiota, can profoundly influence many facets of the host immune system, including the strength of the immune response to influenza vaccination.  In line with these observations, we observed that short-term administration of antibiotics drastically reduced influenza vaccine-specific antibody production. In particular, antibiotic treatment diminished the frequency and activation status of multiple myeloid cell subsets in the draining lymph nodes at steady-state and following vaccination, with associated impairments in B and TFH cell responses.  Composition and function of gut microbiota communities can be rapidly altered through dietary changes. Therefore, the impact of potential prebiotic and probiotic nutritional interventions on the immune response to influenza vaccination and subsequent infection was assessed. No improvement in antibody responses to influenza vaccination was observed following the nutritional interventions studies. However, oral administration of a propolis formulation led to some improvement in viral control following infection.  Collectively, this investigation indicates that alterations in microbial-associated signals leads to severe impairments in cellular responses crucial to humoral immunity and subsequent vaccine-induced antibody production. Furthermore, by altering the gut microbiota through dietary interventions, there is potential to improve immune responses to vaccination.