The focus of this project will be to identify the viral cis elements and trans factors which determine HCMV tissue-specific expression. To accomplish this goal, the investigator proposes to characterize further mouse transgenic lines with three separate transgenes, MIEP-b gal (major immediate-early promoter attached to the b-galactosidase gene), a truncated form of the promoter (tMIEP-b gal) and another IE promoter, US3IEb-gal, for tissue specific expression by double labeling procedures. The author also proposes to characterize the tissue-specific expression of transgenic lines containing the 72 kDa autoregulatory IE protein (MIEP 72 kDa) as well as to establish transgenic mice with the other autoregulatory IE isoforms (MIEP 86 kDa and MIEP 55 kDa). Transgenic mice will be established with a putative repressor late protein (MIEP 40 kDa or late promoter [LP] 40 kDa) with an overlapping reading frame with the IE isoforms. Phenotypes associated with expression of these proteins, as well as the effects of these viral proteins on MIEP tissue-specific expression, will be determined. The author also proposes to cross b-gal and IE/late HCMV transgenics to examine the potential of these IE/late proteins in activation or repression of MIEP in tissue. In the final part of this project, the author will try to examine potential scenarios involved in activation of MIEP in normally non-expressing cells. Replication of HCMV in monocyte/macrophages, a reservoir and vector for the virus, is linked to differentiation of the cells. The investigator will utilize peripheral blood monocytes from HCMV transgenic mice to identify differentiation events which may activate the promoter.
