In the deepest part of the Earth, scientists have discovered clusters of viruses of enormous size, even surpassing bacteria.
According to National Geographic, a team of researchers from Shanghai removed sediments from the seabed, in which they found a colony of viruses, including very large species. Mimiviruses were previously found in other parts of the planet, but it was here, due to high pressure – 1100 times more than atmospheric pressure – that they reached anomalous sizes.
Mimiviruses are a species of Acanthamoeba polyphaga mimivirus, hosted by the amoeba Acanthamoeba. Only in October 2011 it was proved that mimivirus is not the largest in nature: then the even larger Megavirus chilensis was described. Previously, it was believed that mimivirus has the largest capsid – about 500 nm in diameter. Unlike most other viruses, mimivirus is visible under a light microscope and does not pass through a filter with a pore diameter of 0.22 microns.
In the Mariana Trench, the mimivirus population was about 4% of the total viral population. In total, 15 different types of viruses and more than 100 types of other microorganisms were raised from the bottom.
In addition to size, mimivirus differs from other viruses in its very complex genome, which contains more than 1.2 million base pairs. For example, the genomic sequence of the COVID-19 virus is 40 times shorter. The effect of mimivirus on organisms is still being studied. So, in a number of experiments, he was able to cause tissue damage in mammals, but there is still no evidence that mimivirus can be dangerous for humans.
According to one theory, mimiviruses underwent “reverse evolution”, that is, they turned from microbes into viruses, but at the same time retained many productive functions in their genes. It is believed that these genes may have played a role in the struggle for survival in extreme conditions of great depth. Thus, the analysis showed that a giant virus can use productive genes to help its hosts – fungi or unicellular ones, accelerating the breakdown of absorbed carbohydrates, and accelerated metabolism and growth can give hosts and viruses an advantage in the competition.
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