Phylogenetic evidence of uncharacterized Mimivirus relatives. (a) Neighbor-joining (NJ) clustering (see Materials and Methods) of Mimivirus R449 ORF with its best matching (≈35% identical residues) environmental homologues (noted Sargasso1 to Sargasso6 according to their decreasing similarity) and closest viral orthologues (28% identical). (b) NJ clustering of Mimivirus R429 ORF with its best matching (≈50% identical) environmental homologues (noted Sargasso1 to Sargasso5) and closest viral orthologues (35% identical). (c) NJ clustering of Mimivirus putative virion packaging ATPase L437 with its best matching (≈45% identity) environmental homologues (Sargasso1 and Sargasso2) and closest viral orthologues (34% identical). Abbreviations: Phyco: Phycodnavirus; PBCV: Paramecium bursaria chlorella virus 1; EsV: Ectocarpus siliculosus virus; FsV: Feldmannia sp. virus; HaV: Heterosigma akashiwo virus; Irido: Iridovirus; LCDV: Lymphocystis disease virus 1; Frog: Frog virus 3; Amby: Ambystoma tigrinum stebbensi virus; Rana: Rana tigrina ranavirus; Chilo: Chilo iridescent virus. Bootstrap values larger than 50% are shown. Branches with lower values were condensed.