Simian virus 40 associates with nuclear superstructures at early times of infection

The association of infecting simian virus 40 with insoluble nuclear structures was assayed by disrupting infected nuclei and assaying insoluble fractions for virus. Three methods were used which lyse nuclei but maintain the insolubility of residual nuclear structures: sonication, high-salt-Triton-EDTA extraction, and low-salt-lithium diiodosalicylate extraction. After each type of nuclear extraction, infecting simian virus 40 remained associated with the residual nuclear structures. This association depended strictly on natural viral infections and on the use of buffers containing moderate amounts of salt and Mg2+ for the isolation of infected nuclei. These viral interactions exhibited behavior similar to host cell DNA interactions studied by analogous assays. Both viral DNA and coat proteins were found associated with the host cell nuclear superstructure. We concluding that at early times after infection the viral templates mimic the state of the host cell chromatin by attaching to the cellular nuclear matrix.