Experiments dealing with the requirements for expression of eukaryotic genes linked to papovaviral vectors are proposed. A large variety of plasmids carrying replicon sequences from polyoma virus, SV40, bovine papilloma virus and human papovavirus BK will be utilized. To these plasmids will be added, in some cases, the thymidine kinase gene from herpes simplex virus type I. Both morphological and biochemical transformation of normal and thymidine kinase mutant cell lines will be performed. Subsequently, the state and arrangement of plasmid-viral DNA sequences will be characterized. We anticipate that certain host cell lines will maintain specific plasmid-viral recombinants in a free replicating form which can be recovered after transformation of E. coli with nonchromosomal DNA preparations. Studies of transcription and translation of cloned mouse immunoglobulin genes inserted into the late gene region of papovaviral vectors will be performed using lytic propagation with SV40 early mutant helpers. Finally, SV40 or BK virus genomes will be linked to transforming sequences of adenovirus types 2 and 5 of bovine papilloma virus to examine gene expression from these transforming regions and biological properties of the primate cell lines carrying such recombinants.