Expression of the immediate early antigens of human cytomegalovirus is responsible for virus proliferation; an intracellular immunization approach

Abstract

The purpose of this study was to determine the sequence within the immediate early (IE) region of human cytomegalovirus (HCMV) that is the most important in HCMV proliferation. Stable DNA-transfected VA/13 cell lines that express the immediate early antigens (IEA's) of HCMV were established and immunofluorescence staining with patients' antibodies revealed that the transfected DNAs were stable and able to express HCMV-IEA's. A cell line (VA/13-mt) that was transformed with a metallothionein (MT)-promoter was able to express IEA's constantly in 80-90% of cultured cells. Under this condition, VA/13-mt cells produced over 50 times the number of HCMV particles produced by parental VA/13 cells. However, another cell line (VA/13-PX) that was transformed with a fragment deleted at the region of EcoRI H of HCMV DNA did not produce as many HCMV particles as the parental VA/13 cells. These findings indicate that IEA's are responsible for virus proliferation, and that the products from a deleted gene of the IE region may contribute to intracellular immunization.