Posts Tagged “mamavirus”

Giant mamavirus particles (red) and satellite viruses of mamavirus called Sputnik (green).Once upon a time, in 2003, a French team discovered a giant virus infects amoeba. It was isolated from a cooling tower in the UK. They were so excited because it was so huge with a genome contains 900 protein-encoding genes (The words giant/ huge are totally hilarious. It’s not “Hulk”, it’s just a virus). It’s visible under the optical microscope. They named it Acanthamoeba polyphaga mimivirus (APMV). The prefix “mimi” is for mimicking microbe. Now, the same team “Raoult’s team” reported the isolation of another strain of those giant viruses but this time it was isolated from a cooling tower in Paris. They named it “mamavirus” because it was slightly larger than the previous giant virus (APMV), but it wasn’t alone. It was associated with its satellite, a small virus has 21 protein-encoding genes infects it, hijacks its viral factory making copies of itself, hindering the ability of the mamavirus to replicate/ make its own copies, so the number of the mamavirus drops in the infected amoebae. They named it Sputnik after the first man-made satellite. It’ll be the first isolated “Virophage”. How did I know about it? From the amazing blog of Dr. Ramy K. Aziz, “Microbes“.

The story won’t stop at this discovery. The discovery of the virophage will strongly suggest that “Viruses are alive” because they share something with other living domains of life, they can be infected, they can get sick, what makes all health-care providers totally thrilled because there’s something stronger than viruses which could be used to fight them, but “It’s too early to say we could use Sputnik as a weapon against big viruses or to modify them,” says co-author Bernard La Scola.

One more thing about Sputnik, 3 of its genes are closely related to APMV which suggests horizontal gene transfer between giant viruses caused by Sputnik. This is so “bacteriophagic”, reminds me with the whole insertion/ lysogenic mechanism between phages & bacteria. The isolated sequences from the ocean are closely related to the genome sequences of giant viruses & their satellite (Sputnik) . They infect plankton. “It suggests there are other representatives of this viral family out there in the environment,” Koonin says.

Image credits:
Giant mamavirus particles (red) and satellite viruses of mamavirus called Sputnik (green). http://www.nature.com/

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