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 4 th 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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