Working Backwards

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Science  29 Jan 2010:
Vol. 327, Issue 5965, pp. 505
DOI: 10.1126/science.327.5965.505-a

What do you get when you throw anti-idiotypic antibodies into the Sargasso Sea? Well, probably not even a tiny splash, but conceptually what can be harvested is a bounty of previously undescribed and unsuspected virus genomes. When viruses infect plants, the plants fight back by generating an immune response that makes use of and is tailored to the specific virus; small RNAs, roughly 21 to 25 nucleotides in size, are synthesized by the host and used to target and destroy complementary viral RNAs. In developing a diagnostic method for two sweet potato viruses that cause corky lesions in the roots, Kreuze et al. discovered that it was possible through deep sequencing technology to recover the viral genomes by assembling the overlapping sequences of the small RNAs produced by infected plants. In addition to the expected culprits, they identified new members of the badnavirus and mastrevirus genera, which contain species that infect banana and sugarcane plants, respectively. Wu et al. have analyzed libraries of small RNA sequences derived from the fruit fly and the mosquito, and they were also able, via deep sequencing and metagenomic analysis, to identify the presence of a number of new viruses, whose complete genomes could then be reconstructed by PCR.

Virology 388, 1 (2009); Proc. Natl. Acad. Sci. U.S.A. 107, 10.1073/pnas.0911353107 (2010).

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