Inspecting the viral proteome is challenging, as the majority of viral sequences are redundant and poorly annotated. Importantly, the rapid evolution and the high mutation rate in some viral classes often leads to the loss of a detectable sequence similarity and, therefore, additional cases of virus hijacking events cannot be detected based on sequence similarity search methods. Despite these drawbacks, we have traced hundreds of viral proteins with respect to their hosts. Only a small fraction of them shows high sequence similarity with corresponding host proteins. For the majority of the cases, the origin of the viral sequences and possible derivations from the host call for applying powerful models for remote homologues.