Cyclic Structure of Adenovirus DNA

The deoxyribonucleic acids of adenovirus types 2, 7, and 12 were extracted and examined in the electron microscope. Cyclic forms of the molecules were found to exist in each viral type. The lengths of cyclic strands extracted from the most dense fraction of purified particles of adenovirus type 2 were highly variable, averaging about 2.5 microns. This corresponds to a molecular weight of about 5 million.