Immunoprecipitation of virus-specific immediate-early and early polypeptides from cells lytically infected with human cytomegalovirus strain AD 169

By immunoprecipitation of human cytomegalovirus-infected cell-specific polypeptides (ICPs) with a variety of human cytomegalovirus-positive sera and analysis by electrophoresis on sodium dodecyl sulfate-polyacrylamide gels, we can identify at least 20 ICSP bands from lytic infections by 6 hr postinfection (pi). Three of these polypeptide bands (78K, 73K, and 68K) may represent more than one species of polypeptide. Four polypeptide bands (78K, 77K, 73K, and 31K) can be identified as immediate-early based on their synthesis in the presence of actinomycin-D after removal from a protein synthesis block mediated by cycloheximide (CH). An immediate-early 78K polypeptide and an early 49K polypeptide are synthesized only transiently during the first 4 hr pi. Most immediate-early polypeptide synthesis is enhanced after removal of a 5 hr CH block. Taken together, these results identify many previously undetected immediate-early and early ICSPs and suggest that several regulatory events are occurring during the early phase of the lytic cycle.