title: Transcriptome profiling during a natural host-parasite interaction.
abstract: BACKGROUND
  Infection outcome in some coevolving host-pathogens is characterised by host-pathogen genetic interactions, where particular host genotypes are susceptible only to a subset of pathogen genotypes. To identify candidate genes responsible for the infection status of the host, we exposed a Daphnia magna host genotype to two bacterial strains of Pasteuria ramosa, one of which results in infection, while the other does not. At three time points (four, eight and 12 h) post pathogen exposure, we sequenced the complete transcriptome of the hosts using RNA-Seq (Illumina).
  
  
  RESULTS
  We observed a rapid and transient response to pathogen treatment. Specifically, at the four-hour time point, eight genes were differentially expressed. At the eight-hour time point, a single gene was differentially expressed in the resistant combination only, and no genes were differentially expressed at the 12-h time point.
  
  
  CONCLUSIONS
  We found that pathogen-associated transcriptional activity is greatest soon after exposure. Genome-wide resistant combinations were more likely to show upregulation of genes, while susceptible combinations were more likely to be downregulated, relative to controls. Our results also provide several novel candidate genes that may play a pivotal role in determining infection outcomes.
authors: Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, EH9 3JT, UK. smctagga@staffmail.ed.ac.uk.
authors: Seanna J
authors: SJ
authors: McTaggart
authors: Edinburgh Genomics, Ashworth Laboratories, University of Edinburgh, Edinburgh, EH9 3JT, UK. timothee.cezard@ed.ac.uk.
authors: Timothée
authors: T
authors: Cézard
authors: Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, EH9 3JT, UK. j.garbutt@ed.ac.uk.
authors: Jennie S
authors: JS
authors: Garbutt
authors: Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, EH9 3JT, UK. pwilson6@staffmail.ed.ac.uk.
authors: Phil J
authors: PJ
authors: Wilson
authors: Institute of Evolutionary Biology, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, EH9 3JT, UK. tom.litttle@ed.ac.uk.|Centre for Immunity, Infection and Evolution, School of Biological Sciences; Ashworth Laboratories, University of Edinburgh, Edinburgh, EH9 3JT, UK. tom.litttle@ed.ac.uk.
authors: Tom J
authors: TJ
authors: Little
mesh_terms: D000818:Animals; D003621:Daphnia / Q000235:genetics; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006790:Host-Parasite Interactions / Q000235:genetics*; D058676:Pasteuria / Q000235:genetics; D014158:Transcription, Genetic; D059467:Transcriptome