In this paper, we present a coherent survey on protein sequences that are shared between viruses and their hosts. We assess the scale of the phenomenon by focusing on the viral-related protein sequences that appear in metazoa. We have used the current archive of all proteins [31] as the basis for identifying sequences with a potentially common origin. Presumably, their appearance in the virus reflects virus-acquired sequences. Of about 190 instances of highly similar viral-eukaryotes sequences, we recognize that only a small number originated from a host origin. We extended the collection of viral proteins that have a host origin by investigating the eukaryotes-viruses Pfam families [32] .