Synthesis of defective viral DNA in HeLa cells infected with adenovirus type 3.

Virus-specific DNA fragments that are shorter than the full-length viral genomes have been isolated from HeLa cells productively infected with adenovirus type 3. A number of predominant size classes could be detected by gel electrophoresis and hybridization, and the array of sizes was similar or identical to the selection in DNA purified from incomplete particles of this serotype (E. Daniell, J. Virol. 19:685-708, 1976). A large fraction of these short DNA molecules contained long inverted terminal repetitions, as did DNA molecules from incomplete particles. Restriction analysis showed that these subgenomic molecules consist of sequences from the two molecular ends of the normal genome. These results suggest that the predominance of left-hand end fragments seen in packaged incomplete DNAs results from selective packaging, whereas the predominance of certain size classes of intracellular viral DNA is a function of prepackaging events. The incomplete DNAs were generated at all times during viral DNA replication, and the yield relative to complete DNA did not seem to vary significantly with time or multiplicity of infection or when the virus was propagated on different human cell types.