Structure and Composition of a Small Particle Prepared from a Simian Adenovirus

Abstract

When tissue-culture fluids infected with simian adenovirus SV15 are examined in an electron microscope, either as fresh harvests or after treatment with Genetron, typical mature adenovirus particles are found. These are 65 to 70 m[mu]. in diameter, with an icosahedral capsid built from 252 capsomeres. Also present is a population of small polyhedral particles approximately 20 m[mu]. in diameter. These small particles can be separated from the mature virions by ultra-filtration or density gradient centrifugation. The small particles have a density of 1.43 in cesium chloride. They contain protein and double-stranded deoxyribonucleic acid. They appear to possess cubic symmetry of the icosahedral type, with a coat composed of 12 subunits each at the vertex of an icosahedron.