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Paper text:
the genomes of the two mimivirus strains , the mamavirus and apmv , are highly similar but show characteristic divergence in the terminal regions .
the mamavirus genome is the largest available virus genome , in part due to the presence of a 13-kb unique 5-terminal region that apparently evolved by duplication of internal genomic sequences , possibly combined with the acquisition of a dna fragment from an unknown source .
a comprehensive comparative sequence analysis of the mamavirus and apmv proteins led to a substantial amendment of the functional annotation of the mimivirus genome and revealed several unique predicted proteins in the mamavirus .
supplementary methods and files 13 are available at genome biology and evolution online ( http://www.gbe.oxfordjournals.org/ ) .
the genome sequence of the mamavirus , a new acanthamoeba polyphaga mimivirus strain , is reported . with 1,191,693 nt in length and 1,023 predicted protein - coding genes , the mamavirus has the largest genome among the known viruses . 
 the genomes of the mamavirus and the previously described mimivirus are highly similar in both the protein - coding genes and the intergenic regions . 
 however , the mamavirus contains an extra 5-terminal segment that encompasses primarily disrupted duplicates of genes present elsewhere in the genome . 
 the mamavirus also has several unique genes including a small regulatory polya polymerase subunit that is shared with poxviruses . 
 detailed analysis of the protein sequences of the two mimiviruses led to a substantial amendment of the functional annotation of the viral genomes .