Samples of giant mimiviruses were found at the bottom of the Mariana Trench. They grew due to pressure at a depth of 11 km.
A group of Chinese researchers, as part of the Challenger Deep mission, removed sediments from the deepest point on the planet. Scientists found viruses in them, among which there were giant species. The authors of the study note that their size was larger than that of some bacteria, which is very unusual. Although mimiviruses have been found elsewhere, they were found to be more abundant at a depth of 11 km. As you know, the pressure in this area is 1100 times higher than atmospheric.
Mimiviruses are a genus of viruses that includes the only species, Acanthamoeba polyphaga mimivirus (APMV), and are hosted by the amoeba of the genus Acanthamoeba. Unlike most other viruses, mimivirus does not pass through a filter with a pore diameter of 0.22 microns and is visible under a light microscope.
The mimivirus population at the bottom of the trench is approximately 4% of the total viral population. Also, along with the sediments, scientists extracted 15 other types of viruses and more than 100 bacteria of different types from the ocean floor. In addition to its abnormal size, mimivirus is distinguished from other pathogens by a very complex genome – it contains more than 1.2 million base pairs. For comparison, the genome of the new type of coronavirus that provoked the COVID-19 pandemic is almost 40 times shorter. Scientists emphasize that the effect of mimiviruses on mammals is still only being studied in laboratory conditions.