Abstract
The structure of unintegrated spleen necrosis virus DNA was characterized by using various chemical and enzymatic treatments in conjunction with denaturing gels and nucleic acid hybridization probes. Throughout the course of the viral infection, the predominant species of viral DNA was that of a linear double-stranded molecule containing ribonucleotides covalently joined to the DNA. The majority of both - and + strands were continuous. The ribonucleotide linkages appeared to be relatively short, and the base composition and distribution of the ribonucleotide linkages were heterogeneous. On the average, the - strand had fewer of the ribonucleotide linkages than did the strand. Viral DNA containing ribonucleotide linkages was infectious in DNA transfection assays. The structure of spleen necrosis virus DNA was different from that of Schmidt-Ruppin Rous sarcoma virus-D, and mixed infections demonstrated that the observed differences are a result of cis-acting functions.