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The viral and cellular “empires” of life forms and domains within them. The cellular empire domains: A, Archaea; B, Bacteria; E, Eukaryota. The Virus empire domains: +R, positive-strand RNA viruses; −R, negative-strand RNA viruses; dsR, double-stranded RNA viruses; dsD, double-stranded DNA viruses; ssD, single-stranded DNA viruses; RT, retro-transcribing elements/viruses; VR, viroids.
