Formation and structure of infectious DNA of spleen necrosis virus

Abstract

The kinetics of formation and the structure of infectious DNA of spleen necrosis virus [in chicken embryo fibroblasts] were determined. Nonintegrated infectious viral DNA 1st appeared 18-24 h after infection of dividing cells and persisted for > 14 days. The nonintegrated infectious viral DNA was in the form of either a double-stranded linear DNA with a MW of 6 .times. 106, detected in both the cytoplasm and nucleus, or a closed circular DNA of the same molecular weight, detected primarily in the nucleus. Integrated infectious viral DNA appeared soon after the nonintegrated infectious viral DNA and was the predominant form of infectious viral DNA late after infection. Integration of the spleen necrosis virus DNA into the chicken cell genome was demonstrated by 3 independent crtieria. Nucleic acid hybridization indicated that the linear infectious viral DNA had a 5- to 10-fold higher specific infectivity than the closed circular or integrated infectious viral DNA. Infectious viral DNA did not appear in infected stationary cells, indicating some cellular influence on the formation of infectious viral DNA.