EQUINE HERPESVIRUS TYPE-1 INFECTED CELL POLYPEPTIDES - EVIDENCE FOR IMMEDIATE EARLY EARLY LATE REGULATION OF VIRAL GENE-EXPRESSION

EHV-1 [equine herpes virus type 1) polypeptide synthesis was examined in productively infected rabbit kidney and hamster embryo cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses of extracts from [35S]methionine- and 3H-amino acid-labeled-infected and mock-infected cultures revealed the presence of 30 infected cell-specific polypeptides (ICP) which ranged in apparent MW from 1605 K (16,500)-213 K. Of these ICP, 22 comigrated with virion structural proteins. Four ICP (203K, 176K, 151K, 129K) were detected in extracts of infected cultures labeled in the presence or absence of actinomycin D (Act D) immediately after release from a 4-h treatment with cycloheximide (CH). These polypeptides, which were designated as EHV-1 immediate early (.alpha.) ICP, were not detected in unblocked (non-CH-treated) infected cells. The most abundant ICP was a 31.5K nonstructural protein which, in addition to a 74K protein, was detected in unblocked infected cells, at 2-3 h postinfection. These proteins appeared to be regulated as early (.beta.) ICP, since neither protein was observed in Act D-treated cultures released from CH block. Twelve ICP were classified as late (.gamma.) polypeptides on the basis of their reduced synthesis in cultures in which viral DNA replication was inhibited by phosphonoacetic acid. All but 1 (40K) of these late ICP corresponded to virion structural proteins.