The Anatomy of Viral DNA Molecules

Abstract

A few species of virions contain single polydeoxyribonucleo-tides in circular form. Another group contains circular duplexes. A larger number of species contain linear duplex molecules. Most of the species contain uninterrupted duplex molecules; others contain natural interruptions at specific locations in the molecule. Some viral DNA molecules are circularly-permuted collections of sequences, others are unique collections. Both types are terminally repetitious. In some cases, the linear DNA molecules are converted into circular ones inside the host cell shortly after infection. Viral DNA molecules vary in composition along the molecule, and different regions are composed of complementary chains having detectable differences in composition. Genes occupy the same relative positions on the genetic map and the DNA molecule. The orientation of these genes can be opposed, indicating that different regions of either chain can be transcribed and translated.