The within-host dynamics of infection in trans-generationally primed flour beetles

Mol Ecol. 2017 Jul;26(14):3794-3807. doi: 10.1111/mec.14088. Epub 2017 Apr 4.


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.

Keywords: Bacillus thuringiensis; Tribolium castaneum; EIF4-e; gene expression; metabolism; trained immunity; trans-generational immune priming.

MeSH terms

  • Animals
  • Bacillus thuringiensis*
  • Disease Resistance / genetics*
  • Female
  • Transcriptome
  • Tribolium / genetics*
  • Tribolium / microbiology*

Associated data

  • GENBANK/GSE95387