title: The within-host dynamics of infection in trans-generationally primed flour beetles.
abstract: Many taxa exhibit plastic immune responses initiated after primary microbial exposure that provide increased protection against disease-induced mortality and the fitness costs of infection. In several arthropod species, this protection can even be passed from parents to offspring through a phenomenon called trans-generational immune priming. Here, we first demonstrate that trans-generational priming is a repeatable phenomenon in flour beetles (Tribolium castaneum) primed and infected with Bacillus thuringiensis (Bt). We then quantify the within-host dynamics of microbes and host physiological responses in infected offspring from primed and unprimed mothers by monitoring bacterial density and using mRNA-seq to profile host gene expression, respectively, over the acute infection period. We find that priming increases inducible resistance against Bt around a critical temporal juncture where host septicaemic trajectories, and consequently survival, may be determined in unprimed individuals. Our results identify a highly differentially expressed biomarker of priming, containing an EIF4-e domain, in uninfected individuals, as well as several other candidate genes. Moreover, the induction and decay dynamics of gene expression over time suggest a metabolic shift in primed individuals. The identified bacterial and gene expression dynamics are likely to influence patterns of bacterial fitness and disease transmission in natural populations.
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA.
authors.forename: Ann T
authors.identifier: http://orcid.org/0000-0001-6601-0234
authors.initials: AT
authors.lastname: Tate
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Andolfatto
authors.affiliation: Department of Biology, University of Texas, Arlington, TX, 76010, USA.
authors.forename: Jeffery P
authors.initials: JP
authors.lastname: Demuth
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA.
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Graham
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis; D060467:Disease Resistance / Q000235:genetics*; D005260:Female; D059467:Transcriptome; D014231:Tribolium / Q000235:genetics* / Q000382:microbiology*
keywords: 
  Bacillus thuringiensis
  ; 
  Tribolium castaneum
  ; EIF4-e; gene expression; metabolism; trained immunity; trans-generational immune priming