Based on the bioinformatic evidence generated here, it seems reasonable to assume that the viral AlkB domains identified by Pfam are functional. All the essential residues found in 2-oxoglutarate-and Fe(II)-dependent oxygenases are conserved, in particular the putative Fe 2+ coordinating H, D and H residues at alignment positions 19, 21 and 91 of Figure 3 , and the 2-oxoglutarate coordinating R at position 100. The conserved R at position 106 is also very characteristic of AlkB homologues [10] . The fact that all AlkB-like domains identified in these viral genomes are full-length, compared to the Pfam profile, also seems to support the hypothesis that these domains are functional.