Viruses in the Floreoviria realm are eukaroytic viruses with circular single-stranded DNA genomes that encode a specific"replication initiation endonuclease (Rep)":/preview_by_species/10817. Their capsids are icosahedral with T=1 symmetry, built from a single jelly roll (SJR) fold. Due to the simplicity and universal replication mechanism, these viruses are very versatile and can jump to new hosts and evolve rapidly.