Adenoviral protein VII packages intracellular viral DNA throughout the early phase of infection.

The proteins associated with parental, adenoviral DNA in productively‐infected HeLa cells have been examined both directly and indirectly. HeLa cells infected with 32P‐labelled Ad2 were irradiated with u.v. light at various points in the infectious cycle. Following degradation of the DNA, nuclear proteins carrying cross‐linked nucleotides, or oligonucleotides, were distinguished from virion phosphoproteins by the resistance of their 32P radioactivity to 1 M NaOH. The major core protein of the virion, protein VII, was found to be associated with viral DNA throughout infection, even when cells were infected at a multiplicity of 0.14. Micrococcal nuclease digestion of intranuclear viral DNA 4 h after infection liberated two nucleoprotein particles containing viral DNA, neither of which co‐migrated with HeLa cell mononucleosomes. These results indicate that core protein VII remains associated with parental adenoviral DNA during productive infections. The observation that protein VII can be cross‐linked to DNA in cells infected at very low multiplicity, together with the results of a comparison of proteins cross‐linkable to viral DNA in cells infected by wild‐type virus and a non‐infectious mutant containing the precursor to protein VII, suggest that nucleoproteins comprising viral DNA and protein VII must be the templates for expression of pre‐early and early viral genes.