This proposal is concerned with the following problems: (1) The elucidation of the transcriptional controls operating in various cell lines infected with different types and strains of herpes simplex virus (HSV). (2) The identification of the functions of the "immediate-early" proteins of the herpes viruses and the exploration of the use of antisera against these proteins as probes to detect viral products in cells experimentally transformed by HSV and pseudorabies (Pr) virus and in cells putatively naturally transformed by HSV. (3) The characterization of interactions of HSV, types 1 and 2, and of Pr virus with cells transformed by RNA tumor viruses. (4) The characterization of the viral glycoproteins excreted by infected cells. Special emphasis on the possible use of these glycoproteins as diagnostic tools. (5) The characterization of the DNA molecules present: (a) in populations of recently plaque-purified virions, (b) in standard virions passaged several times at low multiplicity, (c) in several different isolates of populations of defective, interfering virions. (6) The characterization of the replicative forms of the viral DNA in cells infected with the virions listed in 5.