Virophages and retrotransposons colonize the genomes of aquatic flagellates

  • Hackl, T. (Speaker)
  • Sarah Duponchel (Contributor)
  • Anna Koslova (Contributor)
  • Matthias G Fischer (Contributor)

Activity: Talk and presentationAcademic presentationAcademic


Virophages can parasitize giant DNA viruses and may provide adaptive anti-giant virus defense in unicellular eukaryotes. Under laboratory conditions, the virophage mavirus integrates into the nuclear genome of the marine flagellate Cafeteria burkhardae and reactivates upon superinfection with the giant virus CroV. In natural systems, however, the prevalence and diversity of host-virophage associations has not been systematically explored. Here, we report dozens of integrated provirophages in bicosoecid flagelates from marine and fresh-water environments, includuing 8 types of mavirus-like virophages in four globally sampled C. burkhardae strains. The latter account for up to 2% of their hosts’ genomes and based on promoter motifs likely interact with different giant viruses. Between hosts, some provirophage loci were conserved indicating ancient integration events, whereas the majority of insertion sites were unique to a given host suggesting that these viruses are active and mobile. Furthermore, we uncovered a unique association between virophages and a group of tyrosine recombinase retrotransposons, revealing yet another layer of parasitism in this nested microbial system. Our findings show that virophages are widespread and dynamic in wild bicoecid populations, supporting their potential role in antiviral defense in protists.
Event titleNetherlands Annual Ecology Meeting 2022
Event typeConference
Conference number15
Organiser Netherlands Ecological Research Network (NERN)
LocationLunteren, NetherlandsShow on map
Degree of RecognitionNational