The end of a 60-year riddle: identification and genomic characterization of an iridovirus, the causative agent of white fat cell disease in zooplankton

Elena R. Toenshoff, Peter D. Fields, Yann X. Bourgeois, Dieter Ebert

Research output: Contribution to journalArticlepeer-review

31 Downloads (Pure)

Abstract

The planktonic freshwater crustacean of the genus Daphnia are a model system for biomedical research and, in particular, invertebrate-parasite interactions. Up until now, no virus has been characterized for this system. Here we report the discovery of an iridovirus as the causative agent of White Fat Cell Disease (WFCD) in Daphnia WFCD is a highly virulent disease of Daphnia that can easily be cultured under laboratory conditions. Although it has been studied from sites across Eurasia for more than 60 years, its causative agent had not been described, nor had an iridovirus been connected to WFCD before now. Here we find that an iridovirus-the Daphnia iridescent virus 1 (DIV-1)-is the causative agent of WFCD. DIV-1 has a genome sequence of about 288 kbp, with 39% G+C content and encodes 367 predicted open reading frames. DIV-1 clusters together with other invertebrate iridoviruses but has by far the largest genome among all sequenced iridoviruses. Comparative genomics reveal that DIV-1 has apparently recently lost a substantial number of unique genes but has also gained genes by horizontal gene transfer from its crustacean host. DIV-1 represents the first invertebrate iridovirus that encodes proteins to purportedly cap RNA, and it contains unique genes for a DnaJ-like protein, a membrane glycoprotein and protein of the immunoglobulin superfamily, which may mediate host-pathogen interactions and pathogenicity. Our findings end a 60-year search for the causative agent of WFCD and add to our knowledge of iridovirus genomics and invertebrate-virus interactions.

Original languageEnglish
Pages (from-to)1259-1272
Number of pages14
JournalG3: Genes, Genomes, Genetics
Volume8
Issue number4
Early online date27 Feb 2018
DOIs
Publication statusPublished - 28 Mar 2018

Keywords

  • Animals
  • Base Composition/genetics
  • Conserved Sequence
  • Cytoplasm/virology
  • Daphnia/virology
  • Genes, Viral
  • Genome Size
  • Genome, Viral
  • Genotype
  • Iridovirus/genetics
  • Open Reading Frames/genetics
  • Phylogeny
  • RNA Caps/genetics
  • Sequence Homology, Nucleic Acid
  • Viral Proteins/genetics
  • Virion/ultrastructure
  • Zooplankton/virology

Fingerprint

Dive into the research topics of 'The end of a 60-year riddle: identification and genomic characterization of an iridovirus, the causative agent of white fat cell disease in zooplankton'. Together they form a unique fingerprint.

Cite this