Mimiviridae

Mimiviridae is a family of viruses known for their exceptionally large size and complex genomes. These viruses, often referred to as mimiviruses, belong to the order Megavirales. They are obligate intracellular parasites, meaning they can only replicate inside living host cells. The first mimivirus to be discovered, *Mimivirus* (also known as *Acanthamoeba polyphaga mimivirus*), was identified in 2003, infecting amoebas.

The virions of mimiviruses are typically spherical and have a diameter of around 750 nanometers, making them visible under a light microscope, a feature unusual for viruses. Their genomes are also remarkably large, containing millions of base pairs and encoding thousands of genes, some of which are involved in processes previously thought to be unique to cellular organisms, such as amino acid synthesis and protein repair. This complexity has led to debate about the definition of life and the evolutionary origins of viruses.

Mimiviruses are currently classified into a single genus, *Mimivirus*, and the family Mimiviridae contains several recognized species, including *Acanthamoeba polyphaga mimivirus* and *Megavirus chilensis*. Their discovery has significantly expanded our understanding of viral diversity and evolution, prompting a re-evaluation of the boundaries between viruses and cellular life. Further research continues to explore their unique biology and ecological roles.