Searches for similarities were mainly developed using facilities of BLAST programs at two websites http:// www.ncbi.nlm.nih.gov/blast/Blast.cgi and http:genoweb.univ-rennes1.fr/Serveur-GPO/out ils.php3?id_rubrique=47. For DpAV4 genes having their origin within eukaryotic, bacterial or virus genomes belonging to NCLDV and non-NCLDV families, the closest gene was located using the distance trees supplied with each BLAST search at the NCBI website.