The biggest virus known was discovered back in 2003 by a team of researchers led by Didier Raoult. This virus can be found in single-celled protozoans, and it cannot grow all by itself, so it uses the infected host cells to produce new viruses.
What makes this virus special is that it is extremely big, hundreds of times bigger than other viruses and it has more than 900 genes, which is more than many bacteria. After finding this first giant virus, the scientists continued the search and found more than 150 types of giant viruses around the world, both on land and in the oceans, and of course in animals’ and humans’ body.
The largest type of virus they found has over 2,500 genes, but the researchers did not know what the genes were really for. Thankfully, they managed to find out recently that the great number of genes actually form an immune system for the giant virus.
The virus’s immune system is very similar to the CRISPR system, the gene editing tool. However, it is not yet sure how the immune system of the virus works. If researchers manage to find out and detail the findings, the system could later be harnessed for genetic control purposes.
So far, we know that the immune system of the giant viruses protects them against smaller viruses. The researchers tried to attack a giant virus with Zamilon, a smaller virus supposed to hack the biochemistry of the big ones. But the attack did not go as planned, as the giant virus managed to defend itself.
CRISPR was developed based on the immune defenses of bacteria and works in a way similar to antibodies. When bacteria is infected by a virus, it captures genetic material which stores away and reveals later when they have to deal with a similar virus.
It turns out the new giant viruses have similar abilities, which allow them to recognize a smaller virus and protect themselves against it. The researchers name the giant virus DNA MIMIVIRE. If they also manage to figure out how the immune system works, they might be able to apply it for gene editing just as they did with bacteria.
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