Localization of adenovirus DNA replication in KB cells

Abstract

The localization of adenovirus type 5 DNA replication has been investigated by both fractionation of isolated nuclei and electron-microscope autoradiography. Nuclear fractionation by means of the M-band-technique of Tremblay et al. (Tremblay, G. Y., Daniels, M. J., and Schaechter, M. (1969). J. Mol. Biol. 40, 65–76.) reveals that pulse-labeled adenovirus type 5 DNA cosediments with the nuclear membrane. On the basis of this finding it can be supposed that the site of viral DNA replication is at the nuclear membrane. However, electron-microscope autoradiography of infected cells shows that the pulse-labeled viral DNA is not located at the nuclear membrane but randomly distributed over the nucleus. It is concluded that the replication of adenovirus type 5 DNA occurs throughout the cell nucleus; the association of replicating viral DNA with a nuclear membrane complex should be considered as an artifact.