The proposed research is concerned with the molecular biology of non-defective parvovirus transcription in synchronized cell cultures. The long term goal is to identify and define the nature of the cell-cycle dependency of parvovirus replication and transcription. For the nondefective parvoviruses, initiation of viral DNA transcription is dependent upon one or more host functions expressed transiently in S or G2 phase of the cell cycle. Regulation of host and viral RNA synthesis in vivo is very complex, therefore, we are proposing to examine a less complicated system, i.e., the transcription complex. Transcription complexes will be isolated from bovine parvovirus-infected cells. Cell-free extracts will also be prepared from eukaryotic cells and supplemented with parvovirus DNA. The RNA products synthesized in vitro in transcription complexes and in the cell-free system will be compared to those produced in vivo in order to assess the fidelity of transcription. The complexes will be assayed for endogenous cellular RNA polymerase I, II, and III activities. The RNA polymerase requirement for BPV RNA synthesis in the cell-free system will be determined by sensitivity to alpha amanitin. The ability of the transcription complex and the cell-free system to both initiate and elongate parvoviral RNA in vitro will be determined. The proposed research should contribute to the understanding of regulation of mammalian DNA virus transcription and of cellular RNA synthesis.