The hypothesis was first proposed by Philip Bell in 2001[1] and was further popularized with the discovery of large, complex DNA viruses (such as Mimivirus) that are capable of protein biosynthesis.
Further, the viral origins of the modern eukaryotic nucleus may have relied on multiple infections of archaeal cells carrying bacterial mitochondrial precursors with lysogenic viruses.
Similarly, the bacterial species involved in this eukaryogenesis retained its capacity to produce energy in the form of ATP while also passing much of its genetic information into this new virus-nucleus organelle.
However, this theory is controversial, and additional experimentation involving archaeal viruses is necessary, as they are probably the most evolutionarily similar to modern eukaryotic nuclei.
[8] The eukaryotic nucleus contains linear DNA with specialized end sequences, like that of viruses (and in contrast to bacterial genomes, which have a circular topology); it uses mRNA capping, and separates transcription from translation.
[10] The same researchers also found that this same phage encodes a eukaryotic homologue to tubulin (PhuZ) that plays the role of positioning the viral factory in the center of the cell during genome replication.
[7] Further, many classes of nucleocytoplasmic large DNA viruses (NCLDVs) such as mimiviruses have the apparatus to produce m7G capped mRNA and contain homologues of the eukaryotic cap-binding protein eIF4E.
For instance, a helical virus with a bilipid envelope bears a distinct resemblance to a highly simplified cellular nucleus (i.e., a DNA chromosome encapsulated within a lipid membrane).