ENGULFMENT REMAINS. “For all dsDNA viruses of eukaryotes, we can detect clear ancestry among viruses (and in some cases, plasmids) of bacteria, an observation that is compatible with the key role of the (proto)mitochondrial endosymbiont (and possibly other bacterial symbionts) in the evolution of eukaryotes.”
http://onlinelibrary.wiley.com/doi/10.1111/nyas.12728/full