A search for similarities between viral and host proteins has largely been focused on herpesviruses [27] , Hepadnaviridae [28] and others. However, the high mutation rate of RNA viruses [29] and the coexistence between viruses and their hosts for millions of years has most likely blurred the sequence similarity. Recently, several studies challenged the origin of ancient viral segments in metazoan genomes. These sequences that are called EVE (for endogenous viral element) encompass all virus-derived genomic loci [30] .