Posts Tagged ‘RNA virus’

Endogenous RNA viruses of plants in insect genomes

5 June, 2012

See on Scoop.itVirology News

“Endogenous viral elements (EVEs) derived from RNA viruses with no DNA stage are rare, especially those where the parental viruses possess single-strand positive-sense (ssRNA +) genomes. Here we provide evidence that EVEs that share a sequence similarity to ssRNA + viruses of plants are integrated into the genomes of a number of insects, including mosquito, fruit flies, bees, ant, silkworm, pea aphid, Monarch butterfly, and wasps. A preliminary phylogenetic analysis places these EVEs as divergent relatives of the Virgaviridae and three currently unclassified plant viral species.”

I have covered this before, in ViroBlogy, (and here, in 2007)as an interesting and probably under-appreciated phenomenon.  I note Eddie Holmes and colleagues have now taken it much, much further – which incidentally lends significant credence to my supposition that virus/vector/plant coevolution was probably a fair bit more intimate than has been supposed, with the newly-emerged (in evolutionary terms) insects and their viruses meeting terrestrial plants and THEIR viruses.  And mixing everything up, as I have speculated elsewhere (Origins of Viruses).

I thank Jean-Marie Verchot for drawing my attention to this!

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Biology Direct | Abstract | A novel virus genome discovered in an extreme environment suggests recombination between unrelated groups of RNA and DNA viruses

20 April, 2012

See on Scoop.itVirology News

“Viruses are known to be the most abundant organisms on earth, yet little is known about their collective origin and evolutionary history.  With exceptionally high rates of genetic mutation and mosaicism, it is not currently possible to resolve deep evolutionary histories of the known major virus groups. Metagenomics offers a potential means of establishing a more comprehensive view of viral evolution as vast amounts of new sequence data becomes available for comparative analysis.

Bioinformatic analysis of viral metagenomic sequences derived from a hot, acidic lake revealed a circular, putatively single-stranded DNA virus encoding a major capsid protein similar to those found only in single-stranded RNA viruses. The presence and circular configuration of the complete virus genome was confirmed by inverse PCR amplification from native DNA extracted from lake sediment. The virus genome appears to be the result of a RNA-DNA recombination event between two ostensibly unrelated virus groups.”

Not the first time this is postulated to have happened, although the authors have cited the first one: Gibbs and Weiller, 1999.

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Virus Origins II

28 September, 2011

I have updated the blog on virus origins quite considerably – new pictures, more detail, more speculation!

Pathways on information flow for RNA viruses