title: Immune system stimulation by the native gut microbiota of honey bees.
abstract: Gut microbial communities can greatly affect host health by modulating the host's immune system. For many important insects, however, the relationship between the gut microbiota and immune function remains poorly understood. Here, we test whether the gut microbial symbionts of the honey bee can induce expression of antimicrobial peptides (AMPs), a crucial component of insect innate immunity. We find that bees up-regulate gene expression of the AMPs apidaecin and hymenoptaecin in gut tissue when the microbiota is present. Using targeted proteomics, we detected apidaecin in both the gut lumen and the haemolymph; higher apidaecin concentrations were found in bees harbouring the normal gut microbiota than in bees lacking gut microbiota. Inin vitroassays, cultured strains of the microbiota showed variable susceptibility to honey bee AMPs, although many seem to possess elevated resistance compared toEscherichia coli. In some trials, colonization by normal gut symbionts resulted in improved survivorship following injection withE. coli. Our results show that the native, non-pathogenic gut flora induces immune responses in the bee host. Such responses might be a host mechanism to regulate the microbiota, and could potentially benefit host health by priming the immune system against future pathogenic infections.
authors.affiliation: Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA; Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA.
authors.forename: Waldan K
authors.identifier: 0000-0001-7999-3217
authors.initials: WK
authors.lastname: Kwong
authors.affiliation: Department of Integrative Biology , University of Texas at Austin , Austin, TX , USA.
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Mancenido
authors.affiliation: Department of Integrative Biology , University of Texas at Austin , Austin, TX , USA.
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Moran
keywords: antimicrobial peptides; apidaecin; innate immunity; symbiosis