Brief Review

Archives of Virology

, Volume 147, Issue 8, pp 1479-1516

First online:

Phycodnaviridae– large DNA algal viruses

  • J. L. Van EttenAffiliated with Nebraska Center for Virology and Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska, U.S.A.
  • , M. V. GravesAffiliated with Center for Biotechnology, University of Nebraska, Lincoln, Nebraska, U.S.A.
  • , D. G. MüllerAffiliated with Department of Biology, University of Konstanz, Konstanz, Germany
  • , W. BolandAffiliated with Max-Planck-Institut für Chemische Ökologie, Jena, Germany
  • , N. DelaroqueAffiliated with Department of Biology, University of Konstanz, Konstanz, Germany

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 Members and prospective members of the family Phycodnaviridae are large icosahedral, dsDNA (180 to 560 kb) viruses that infect eukaryotic algae. The genomes of two phycodnaviruses have been sequenced: the 331 kb genome of Paramecium bursaria chlorella virus (PBCV-1) and more recently, the 336 kb genome of the Ectocarpus siliculosus virus (EsV-1). EsV-1 has ∼ 231 protein-encoding genes whereas, the slightly smaller PBCV-1 genome has 11 tRNA genes and ∼ 375 protein-encoding genes. Surprisingly, the two viruses only have 33 genes in common, of which 17 have no counterparts in the databases. The low number of homologous genes between the two viruses can probably be attributed to their different life styles. PBCV-1 is a lytic virus that infects a unicellular, endosymbiotic freshwater green alga whereas, EsV-1 is a lysogenic virus that infects a free-living filamentous marine brown alga. Furthermore, accumulating evidence indicates that the phycodnaviruses and their genes are ancient, thus allowing significant differences to have evolved. This review briefly describes some of the biological properties of the phycodnaviruses, focusing on PBCV-1 and EsV-1, and then compares their genomes.