Studies on DNA from low-density particles of SV40: II. Noninfectious virions associated with a large-plaque variant

Abstract

The purified virions of a large-plaque variant of SV40 consist of two classes of particles of different densities, 1.33 and 1.34 g/cm 3. The lighter virions (1.33) are noninfectious but are immunologically and morphologically indistinguishable from infectious virions (1.34). DNA from noniufectious virions is also defective. The light particles have been shown to contain circular DNA about 12% shorter than that from infectious virions. The difference in density and the defectiveness of light virions are believed to be due to the alteration in the amount of DNA contained in the virions.