MIMIVIRUS. Comparison of the size of a mimivirus 400 nm with the one of a bacterium Escherichia coli, 300nm and of a virus VIH, 80_100 nm with average dimensions. Mimivirus is a giant virus isolated in 2003 in the ameba Acanthamoeba polyphaga, and considered until then as the largest existing virus capsid of 400 nm of diameter, that is bigger than certain bacteria and visible in optical microscopy, which explains its name of mimivirus mimicking microbe virus. In 2008, the mamavirus was discovere