Virophage: virus lives on virus

Viruses are dead and use living cells to multiply. Yet researchers have now discovered virophages in Antarctic Organic Lake, viruses that other viruses need to reproduce. Nature always presents us with surprises ...

The new virophage was discovered by student Sheree Yau and was named Organic Lake Virophage or OLV. She discovered the new virophage when certain amino acid sequences in a protein contained in the virus shell were very similar to the first ever discovered virophagus, Sputnik.

Sputnik (here within a mamavirus) is the first virus discovered that parasitizes other viruses.

Sputnik was discovered in a water cooling tower in Paris in 2008. Earlier this month, Matthias Fischer and Curtis Suttle announced the discovery of a second virophage, the mavirus. The amino acid series is found in many more places in the world, ranging from the Galápagos Islands to the New Jersey chest and a freshwater lake in Panama. So it seems that this type of virus is worldwide.

Virophages can only reproduce in a host if it is infected with another virus. At the first discovered virophagus, Sputnik, this is the giant one mamavirus that infects amoeba. Sputnik hijacks the multiplication process, causing the amoeba to produce many copies of Sputnik instead of the Mamavirus.

The new OLV genome was discovered within the DNA sequences of phycodnaviruses (one at the mother and mimivirus related group of large viruses that infect algae). As it turns out, OLV keeps the number of phycodnaviruses in the lake under control, so that algae can develop to bloom more often.

The discovery of this new group of viruses may help to fight viral diseases such as herpes, hepatitis and AIDS. Latent viruses hiding in a cell are feared. After some genetic manipulation, this new class of viruses may finally be able to deal with this group.

PNAS (abstract; unfortunately no free full-text version available)

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