Endogenous viruses in viruses

Viruses are everywhere.

Theyre even in other viruses.

:-|

A couple of scientists at Portland States 'Center for Life in Extreme Environments' just found a virus in the sediment of Boiling Springs Lake in Lassen Volcanic National Park ('boiling'? 'volcanic'? sounds cozy!). It is a single-strand, circular DNA virus.

Well, okee dokie! Every new virus we find is a good thing-- helps us find new genes that evolution has already invented for us, helps us understand the evolution of viruses, its fun!

But what makes this guy so neat is that it is a DNA virus... with the capsid (structural core, think gag) normally found in RNA viruses. At some point in time, a DNA viruses genome incorporated and domesticated genes from another virus. An RNA virus.

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

The known virosphere consists of three principal viral types; the RNA-only viruses, which do not require a DNA intermediate in the replication cycle, viruses with DNA-based genomes, and retroid viruses that require the reverse transcription of their RNA into DNA during the virus life-cycle. Lateral exchange of viral genes, via multiple possible mechanisms, is rampant among viruses within each of these principal types, but is generally confined to closely related viruses, or viruses (and plasmids) with similar replication mechanisms. Clear examples of recent lateral gene transfer (LGT) from RNA-only to DNA-only viral types have not been observed.

Until now.

We report the discovery of a group of circovirus-like DNA genomes whose common ancestor appears to have incorporated a capsid protein (CP) gene known previously only in RNA viruses. The mechanism responsible for the integration of the RNA virus cistron into the DNA virus, and the point in evolutionary time at which it occurred, are unclear.

And these two scientists didnt just find *this* virus. They used the information they learned form *this* virus to go digging around Craig Venters sequence database, Global Ocean Sampling Expidition, and they found *more* previously uncharacterized viruses with this same phenotype.

What does this mean?

As RNA viruses are believed to evolutionarily precede the emergence of DNA viruses, determining the mechanism responsible for direct recombination between RNA and DNA viruses may help address how genes from the "RNA World" were first incorporated into nascent DNA-based genomes during the putative "Virus World" era, and thus further implicate viruses in the RNA-World to DNA-World transition. In any case, the discovery of the BSL RDHV-like virus group extends the modular theory of virus evolution to encompass a much broader range of possibilities than previously thought.

While this is cool-- One thing that I see that they failed to mention was a potentially novel laboratory tool. There is stuff I use in the laboratory every day that we stole and commercialized from viruses, bacteria, fungi, etc. An enzyme or process that can hybridize RNA and DNA and turn it into a DNA expression vector of some kind, that might be fun...