Collaborative Research: Decoding Virus Leviathans

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Giant viruses are loosely defined as having a genome greater than 280,000 base pairs (bp) and currently there are less than 20 full virus genome sequences in this size range. A cursory analysis of this group immediately reveals a diverse range of viruses including poxviruses, phycodnaviruses (algal viruses), herpesviruses, a bacteriophage and nimaviruses (shrimp white spot syndrome virus). The largest to date is the Acanthamoeba polyphaga Mimivirus at 750 nm diameter with a 1.2-million bp genome. Genome sequence data from these giant viruses can help clarify their taxonomic position. These giant viruses possess novel and typically non-virus genes, many of which encode central cellular functions and metabolic pathways. Preliminary observations by flow cytometry and analysis of the Global Ocean Sampling (GOS) database suggest that giant viruses are extremely abundant in aquatic environments and have been overlooked by biased sampling techniques. Most virus studies look at what passes through a 0.2 micrometer filter. Giant viruses, up to 0.75 micrometers, will be caught on these filters and evade detection. The central hypotheses of this project by Drs. W. Wilson (Bigelow Lab for Ocean Sciences) and S. Wilhelm (Univ Tenn) are that giant marine viruses are ubiquitous, diverse and contain large amounts of novel genetic information. Four algal viruses from current collections and 16 additional giant viruses isolated from seawater are being sequenced in this project. The environmental viruses are being isolated and sequenced by adapting single cell sorting techniques. Once sorted, giant viruses are being amplified by multiple displacement amplification (MDA) to generate Giant Virus Single Amplified Genomes (GV-SAGs) for downstream sequencing. To accomplish this work, the PIs are using state-of-the-art facilities for flow cytometry (Bigelow) and sequence analysis (University of Tennessee/Oak Ridge National Laboratory) coupled with bioinformatics expertise from collaborator Professor Jean-Michel Claverie, a world-leader in giant virus research.This research is being discussed during an informal Café Scientifique program designed to teach the public about the latest ideas in science. The PIs are also incorporating a 3-orders of magnitude (virus, lipids/proteins & DNA) module into the Keller-Bigelow Laboratory Orders Of Magnitude (BLOOM) program, designed to teach Maine high school students about marine ecosystems. The PIs are partnering with the School of Journalism at the University of Tennessee (UT) to bring undergraduate and graduate journalism students into the lab to document this research for the general public.