title: Characterizing the infection-induced transcriptome of Nasonia vitripennis reveals a preponderance of taxonomically-restricted immune genes.
abstract: The innate immune system in insects consists of a conserved core signaling network and rapidly diversifying effector and recognition components, often containing a high proportion of taxonomically-restricted genes. In the absence of functional annotation, genes encoding immune system proteins can thus be difficult to identify, as homology-based approaches generally cannot detect lineage-specific genes. Here, we use RNA-seq to compare the uninfected and infection-induced transcriptome in the parasitoid wasp Nasonia vitripennis to identify genes regulated by infection. We identify 183 genes significantly up-regulated by infection and 61 genes significantly down-regulated by infection. We also produce a new homology-based immune catalog in N. vitripennis, and show that most infection-induced genes cannot be assigned an immune function from homology alone, suggesting the potential for substantial novel immune components in less well-studied systems. Finally, we show that a high proportion of these novel induced genes are taxonomically restricted, highlighting the rapid evolution of immune gene content. The combination of functional annotation using RNA-seq and homology-based annotation provides a robust method to characterize the innate immune response across a wide variety of insects, and reveals significant novel features of the Nasonia immune response.
authors.affiliation: Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America.
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Sackton
authors.affiliation: Department of Biology, University of Rochester, Rochester, New York, United States of America.
authors.forename: John H
authors.initials: JH
authors.lastname: Werren
authors.affiliation: Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Clark
mesh_terms: D000818:Animals; D001424:Bacterial Infections / Q000276:immunology*; D019295:Computational Biology; D013293:Enterococcus faecalis / Q000502:physiology; D005260:Female; D020869:Gene Expression Profiling; D007113:Immunity, Innate / Q000235:genetics*; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D017423:Sequence Analysis, RNA; D012689:Sequence Homology, Nucleic Acid; D012706:Serratia marcescens / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics; D013045:Species Specificity; D014863:Wasps / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology
chemical_list: D019476:Insect Proteins