A virus's virus

Researchers have discovered the first virus to infect another virus, according to a study appearing tomorrow in Nature. The new virus was found living inside a new strain of the viral giant, mimivirus. "This is one parasite living on another parasite, which is really fascinating,"

By | August 6, 2008

Researchers have discovered the first virus to infect another virus, according to a study appearing tomorrow in Nature. The new virus was found living inside a new strain of the viral giant, mimivirus. "This is one parasite living on another parasite, which is really fascinating," linkurl:Michael Rossman,;http://bilbo.bio.purdue.edu/~viruswww/Rossmann_home/index.shtml microbiologist at Purdue University, who was not involved in the study, told The Scientist. linkurl:Didier Raoult;http://www.antimicrobe.org/authors/didier_raoult.asp and colleagues at the Universitee de la Mediterranee in Marseilles, France, discovered Mimivirus in 2003 from a water cooling tower in the UK. It primarily infects amoeba, although antibodies have been found to the virus in some human pneumonia cases. It measures in diameter about 400 nanometers (nm), while medium-sized viruses such as adenovirus and linkurl:HIV;http://www.the-scientist.com/2007/9/1/40/1/ measure closer to 100-200 nm. In this study, Raoult's team found a new strain of mimivirus in water from a cooling tower in Paris. This new strain was even larger than mimivirus, so the researchers named it mamavirus. To their surprise, while examining the new strain with electron microscopy they saw a smaller virus attached to mamavirus. This small virus comprises only 20 genes (mimivirus has more than 900 protein-coding genes) and the researchers named it Sputnik. The team quickly set to work to see what effect Sputnik was having on mamavirus. They found that Sputnik infects the linkurl:replication machinery;http://www.the-scientist.com/article/display/54605/ in mamavirus and causes it to produce deformed viral structures and abnormal capsids, where viral genetic information is stored. It had a similar effect on mimivirus. Because Sputnik's behavior so closely resembles what bacteriophage do to bacteria, the researchers called the new type of virus a virophage, and suspect it may represent a new virus family. The researchers found that Sputnik's genes shared homology with genes from all three domains of life: Archea, bacteria, and eukaria. Some of the genes were homologous to novel sequences that scientists previously detected in a metagenomic study of ocean water. This supports the idea that Sputnik is part of a larger family of viruses, Bernard La Scolla, researcher at the Universitee de la Mediterranee and first author on the paper, told The Scientist. The size of a virus may dictate whether it can be infected by smaller viruses such as Sputnik, he added. For this reason, viruses that affect humans -- like HIV and influenza -- are likely too small to be infected by Sputnik-like viruses, said Rossman. La Scolla added he is sure that there are other giant viruses yet to be identified in the world, but they won't necessarily be infected by smaller viruses. "We need to be lucky to find another Sputnik."


Avatar of: Thomas Broker

Thomas Broker

Posts: 1

August 6, 2008

Perhaps there is a parallel here with adeno-associated virus, a single-stranded DNA parvovirus that strictly depends upon multiple activities of an adenovirus helper for conditioning the host cell and for its own replication.
Avatar of: Steven Anderson

Steven Anderson

Posts: 9

August 6, 2008

"Big fleas have little fleas upon their backs to bite'em; little fleas have lesser fleas and so ad infinitum."
Avatar of: Roberta Ross

Roberta Ross

Posts: 1

August 6, 2008

Isn't it nice to have things we intuitively know to be truth, verified by science!

August 6, 2008

The well-known poem of the smaller fleas was not by Robert Burns but by the author of "Gulliver's travels", Jonathan Swift (1667-1745).
Avatar of: anonymous poster

anonymous poster

Posts: 1

August 7, 2008

While this finding is intriguing, a virus's virus has been found many times a long time ago. For example, satellite tobacco mosaic virus is a parasite of tobacco mosaic virus, which depends entirely on the host virus for its own replication but produces its own virions. There are also many parasitic RNA moleculars that infect some plant RNA viruses, for example,satellite RNAs of cucumber mosaic virus, which depends on the host virus for both replication and encapsidation.\n
Avatar of: Carter Thomasson

Carter Thomasson

Posts: 2

August 7, 2008

though virus in virus had been discovered before (satellite Tobacco Mosaic Virus), it still evokes ideas of potential disease therapies and can provide more information for inspired researchers to benefit. Yes, that's great to know...

August 12, 2008

I guess the fact that virus can get "sick" suggest that they are in fact living creatures although I am sure the controversy will keep going. Perhaps there is a whole world of living creatures with a virus size that we are unable to understand and also perhaps there is a big world of living creatures giant-sized that we also can not understand...Still a long way to get a good picture of the universe we humans are.

August 14, 2008

It is interesting to learn about viral parasite on another virus. There appears to be a hidden message /information / or a fundamental law in building and un-building, making or un-making of molecular constructs in different shapes and kinds that nature follows in its routes to form innumerable types of bio-molecular world.

August 18, 2008

What about Viroids and virusoids such as Potato spindle tuber viroid (PSTV)are they not viral and do they not have a host parasite relationship with their respective genetic host?
Avatar of: anonymous poster

anonymous poster

Posts: 6

August 25, 2008

Virus is not alive. Virus is not organism. Virus is microscopic particle without the machinery to replicate. Virus is something like a toxic organic compound occuring due to a chemical process by radiation ( ultraviolet/UV and its interaction with other radiation ) on the living tissue. Its multiplication / proliferation is influenced by the on-going radiation intensity. The various kinds of viruses are determined by the local radiation ( local radioactive nuclide / radioactive fallout } with naturally exist on its surrounding. If the effects of radiation are terminated, viruses will automatically stop multiplication / proliferation.

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