Viral DNA sequences from incomplete particles of human adenovirus type 7

Large pools of empty viral capsids accumulate in cells infected by subgroup B human adenoviruses. Such infected cells also yield DNA-containing incomplete particles in larger quantities than cells infected with serotypes representing other adenovirus subgroups. DNA isolated from carefully purified classes of Ad7 incomplete particles was analyzed by restriction endonuclease cleavage, gel electrophoresis and electron microscopy. At least 90% of the DNA molecules in each sample consisted of sequences that extended from the left end of the viral genome map by variable lengths toward the right end. The average length of DNA is linearly related to the average buoyant density of the incomplete particles from which the DNA is isolated. The results indicate that each capsid contains one DNA molecule. There is also a specific association of the left end of the viral genome with assembled or assembling capsids. The characteristic distributions of Ad7 incomplete particles may result from intracellular pools of assembly intermediates in which the incompletely packaged DNA has been fragmented in vivo or by shear during preparative procedures.