Horizontal Transfer of Bacterial Cytolethal Distending Toxin B Genes to Insects

Kirsten I. Verster, Jennifer H. Wisecaver, Marianthi Karageorgi, Rebecca P. Duncan, Andrew D. Gloss, Ellie E. Armstrong, Donald K. Price, Aruna R. Menon, Zainab M. Ali, Noah K. Whiteman, Harmit Malik

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Horizontal gene transfer events have played a major role in the evolution of microbial species, but their importance in animals is less clear. Here, we report horizontal gene transfer of cytolethal distending toxin B (cdtB), prokaryotic genes encoding eukaryote-targeting DNase I toxins, into the genomes of vinegar flies (Diptera: Drosophilidae) and aphids (Hemiptera: Aphididae). We found insect-encoded cdtB genes are most closely related to orthologs from bacteriophage that infect Candidatus Hamiltonella defensa, a bacterial mutualistic symbiont of aphids that confers resistance to parasitoid wasps. In drosophilids, cdtB orthologs are highly expressed during the parasitoid-prone larval stage and encode a protein with ancestral DNase activity. We show that cdtB has been domesticated by diverse insects and hypothesize that it functions in defense against their natural enemies.

Original languageEnglish (US)
Pages (from-to)2105-2110
Number of pages6
JournalMolecular biology and evolution
Issue number10
StatePublished - Oct 1 2019


  • Aphids
  • Cytolethal distending toxin
  • DNase
  • Drosophila
  • Horizontal gene transfer

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Molecular Biology
  • Genetics


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