Pandoravirus is a genus of very large viruses. They have the largest genomes of any viral genus. Like the other large viruses "Mimivirus", "Pithovirus" and "Megavirus", "Pandoravirus" infects amoebas. Its genome, with 1.9 to 2.5 megabases of DNA, is twice as large as that of "Megavirus". It differs greatly from the other large viruses in appearance and in genome structure.