A Virus-Infecting Virus: Researchers Use The 454 Sequencing System To Identify A Novel Small Virus Parasitic To Another Virus

09 Nov 2008

Using the Genome Sequencer System from 454 Life Sciences, a Roche company, French scientists have identified a small virus that can actually be parasitic to a larger one. The 50 nm virus, named Sputnik, is associated with a new strain of the giant Acanthamoeba polyphaga mimivirus (APMV) and is believed to represent a currently unknown family of viruses. The study, entitled "The virophage as a unique parasite of the giant mimivirus," appeared in the September 4th issue of Nature (1).


The relationship between Sputnik and the mimivirus appears to be beneficial for Sputnik's viral reproduction. On its own, Sputnik does not replicate very well in amoeba cells. However, when the amoeba is also infected with the mimivirus, Sputnik thrives and multiplies in the viral factory created by the mimivirus. Due to the parallels in its life cycle with bacteriophages, the virus was classified as a "virophage".


The Sputnik genome, as determined by shotgun 454 Sequencing, is an 18-kilobase circular double-stranded DNA and contains genes that are linked to viruses infecting each of the three domains of life: Eukarya, Archaea and Bacteria. Therefore, the virophage could be a vehicle mediating lateral gene transfer between giant viruses. The discovery sheds light onto the unique interactions between viruses and has implications on the evolution of these infectious agents, as is evident from the gene mixing and matching within the virophage.


"This study is yet another example of how 454 Sequencing is enabling discoveries in completely new areas of biology. The highly accurate, long reads of the Genome Sequencer System allowed straightforward de novo assembly of this novel viral species," said Chris McLeod, President and CEO of 454 Life Sciences. "Developing our understanding of viruses and their interactions with one another may facilitate deeper insight into combating infectious diseases."


454 Life Sciences, a center of excellence of Roche Applied Science, develops and commercializes the innovative 454 Sequencing system for ultra-high-throughput DNA sequencing. Specific applications include de novo sequencing and re-sequencing of genomes, metagenomics, RNA analysis, and targeted sequencing of DNA regions of interest. The hallmarks of the 454 Sequencing system are its simple, unbiased sample preparation and long, highly accurate sequence reads, including paired-end reads. The technology of the 454 Sequencing system has enabled hundreds of peer-reviewed studies in diverse research fields, such as cancer and infectious disease research, drug discovery, marine biology, anthropology, paleontology and many more.


(1) La Scola, B., Desnues, C., Pagnier, I., Robert, C., Barrassi, L., Fournous, G., Merchat, M., Suzan-Monti, M., Forterre, P., Koonin, E., Raoult, D. Nature, 2008, Sep 4. 455(7209): 100-4. DOI: 10.1038/nature07218



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Headquartered in Basel, Switzerland, Roche is one of the world's leading research-focused healthcare groups in the fields of pharmaceuticals and diagnostics. As the world's biggest biotech company and an innovator of products and services for the early detection, prevention, diagnosis and treatment of diseases, the Group contributes on a broad range of fronts to improving people's health and quality of life. Roche is the world leader in in-vitro diagnostics and drugs for cancer and transplantation, a market leader in virology and active in other major therapeutic areas such as autoimmune diseases, inflammation, metabolism and central nervous system. In 2006 sales by the Pharmaceuticals Division totaled 33.3 billion Swiss francs, and the Diagnostics Division posted sales of 8.7 billion Swiss francs. Roche employs roughly 75,000 worldwide and has R&D agreements and strategic alliances with numerous partners, including majority ownership interests in Genentech and Chugai. Roche's Diagnostics Division offers a uniquely broad product portfolio and supplies a wide array of innovative testing products and services to researchers, physicians, patients, hospitals and laboratories world-wide. For further information, please visit our website at Roche - We innovate healthcare - From Molecule to Medicine.


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